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Blueberry Crumb Cake

This has definitely been the year of the crumb cake for me. Once I posted my Chocolate Chip Crumb Cake, I looked for every opportunity to make it again and again….and again. We LOVED it!!! Then, blueberry season arrived…I love blueberries. I love blueberry muffins. I love crumb cake. How could I not make a Blueberry Crumb Cake?

Blueberry Crumb Cake. A buttery and moist sour cream coffee cake, full of fresh blueberries and topped with a delicious brown sugar cinnamon crumb topping.

So I did. After all, I’d been buying blueberries 4 pounds at a time! I know. Crazy! But when beautiful organic blueberries arrive en masse…I’m all in!

Blueberry Crumb Cake. A buttery and moist sour cream coffee cake, full of fresh blueberries and topped with a delicious brown sugar cinnamon crumb topping.

Of course, even when blueberries weren’t plentiful, I still managed to post some recipes like Blueberry Pancake Cobbler, Lemon Blueberry Cheesecake Dip and Lemon Blueberry Shortbread Bars. (Where there’s a will, there’s a way.)

Blueberry Crumb Cake. A buttery and moist sour cream coffee cake, full of fresh blueberries and topped with a delicious brown sugar cinnamon crumb topping.

So this cake. Here’s how it goes down. We talked about the importance of room temperature ingredients in my Chocolate Chip Cherry Cheesecake post.

Room temperature is also important in this recipe. But while I don’t cheat in the cheesecake recipe, you can cheat a little bit here. And I don’t mean cheat by not using room temperature ingredients. I mean cheat by speeding up the process. Here are my tips for getting ingredients to room temperature faster.

Blueberry Crumb Cake. A buttery and moist sour cream coffee cake, full of fresh blueberries and topped with a delicious brown sugar cinnamon crumb topping.

Tips to bring your ingredients to room temperature faster:

  • Eggs– Before I begin the recipe, I simply put them in a bowl and cover them with very warm tap water. By the time I’m ready for them in the process, they are ready for me.
  • Butter-Microwave the stick of butter at power level 1. I usually do this for a minute, check it and continue to do it in 1 minute increments until it is soft enough to press my finger into the side without too much pressure. Don’t forget to reset the power level to 1 each time you start the oven again. If you forget, you’ll get an oven full of melted butter. And yes…been there, done that.
  • Sour cream and milk-Mix them together and microwave for 30 seconds. Stir, then check the temperature with your finger. We don’t want it to be warm, it should simply feel like it has no chill to it whatsoever.
Blueberry Crumb Cake. A buttery and moist sour cream coffee cake, full of fresh blueberries and topped with a delicious brown sugar cinnamon crumb topping.

Of course you can skip all of these tips if you remember to set your ingredients out to come to room temperature on their own. If you remember, great. If not, I’ve got you covered.

Now let’s make the crumbs. They’re super easy because we’re melting the butter! (Don’t have to worry about room temperature in this step :) Just melt the butter and mix it with the dry ingredients. Press the mixture firmly in a small bowl and stash it in the fridge while you make the cake.

Blueberry Crumb Cake. A buttery and moist sour cream coffee cake, full of fresh blueberries and topped with a delicious brown sugar cinnamon crumb topping.

I melted the butter to mix it with the dry ingredients, and now we’re chilling it to firm the butter back up again. You could skip this step, but this is what helps form chunky crumbs. Just stash it in the fridge while you make the cake. The butter firms up quickly and it will be ready when you are.

For the cake, you want to whip your butter, sugar and lemon zest until fluffy. If your butter is at a nice room temperature, this shouldn’t be a problem since it’s already soft and ready to incorporate some air through beating.

Blueberry Crumb Cake. A buttery and moist sour cream coffee cake, full of fresh blueberries and topped with a delicious brown sugar cinnamon crumb topping.

It’s important to add the lemon zest at this stage because beating it with the sugar helps infuse the flavor throughout the batter.

Then, add the eggs. If your batter is fluffy and your eggs are at room temperature, you are golden. They will incorporate easily.

Blueberry Crumb Cake. A buttery and moist sour cream coffee cake, full of fresh blueberries and topped with a delicious brown sugar cinnamon crumb topping.

If your eggs are cold, it will chill the butter and you’ll have little lumps of solid butter in your batter. The same will happen if your sour cream and milk are cold. If that happens, just keep going with the recipe. Your texture will likely be a little dense, but it will still be edible.

But hey, that’s not going to happen to you because you’re going to make sure everything is at room temperature. Right? Right!

Blueberry Crumb Cake. A buttery and moist sour cream coffee cake, full of fresh blueberries and topped with a delicious brown sugar cinnamon crumb topping.

Sinking Fruit: Myth or Fact?

Now let’s talk about sinking fruit. We’re about to add the blueberries, but we don’t want them to sink to the bottom of the cake. This cake batter is fairly thick, so it’s possible they wouldn’t sink.

I decided not to risk it and tossed the blueberries with a spoonful of flour before I added them to the batter. It took less than a minute.

I don’t use this method when I make Blueberry Cream Cheese Muffins, but this was a whole cake. One that I didn’t want to make over if the berries sunk.

Blueberry Crumb Cake. A buttery and moist sour cream coffee cake, full of fresh blueberries and topped with a delicious brown sugar cinnamon crumb topping.

Theoretically, the flour helps the berries grab onto the batter and remain suspended. However, if you do a search on this method, you’ll find many who debunk the whole idea. You’ll see tests of muffin batter with and without tossing the berries in flour. Results show little difference.

So flour or no flour? I’m leaving it up to you. I hadn’t gone into this recipe planning to test out that theory. I had one goal…Blueberry Crumb Cake.

Once the berries are folded into the batter (naked or floured), just spread it evenly in the pan.

Blueberry Crumb Cake. A buttery and moist sour cream coffee cake, full of fresh blueberries and topped with a delicious brown sugar cinnamon crumb topping.

Get your crumb mixture out of the fridge because it’s ready for you, just like I told you. You’ll need a fork to break through what has become a solid mass of butter, sugar and yum. I like to break it into big chunks with a fork and then break it up into various sizes as I sprinkle it on top of the cake.

Blueberry Crumb Cake. A buttery and moist sour cream coffee cake, full of fresh blueberries and topped with a delicious brown sugar cinnamon crumb topping.
Blueberry Crumb Cake. A buttery and moist sour cream coffee cake, full of fresh blueberries and topped with a delicious brown sugar cinnamon crumb topping.

Once it bakes, you’ll have a lovely crumb topping a rich berry filled coffee cake. Go ahead and sprinkle it with some confectioner’s sugar. I love the way it looks on top of the chunky textured crumbs.

Blueberry Crumb Cake. A buttery and moist sour cream coffee cake, full of fresh blueberries and topped with a delicious brown sugar cinnamon crumb topping.

Or….make a lemon icing. Yeah, I didn’t think of that until I was typing the recipe up. I kept looking at that zested lemon and wondering if I should have incorporated the juice into the cake batter. But I think the lemon icing is an even better idea.

I added directions in the recipe notes for the icing. I think it would be lovely to drizzle that over the crumbs. And, it will add another bit of lemon flavor to the cake.

I fell hard for crumb cake this year. I don’t eat a lot of sweets for breakfast, but I will make an exception for Chocolate Chip Crumb Cake and Blueberry Crumb Cake. Oh yeah, and scones and umm….muffins…

Blueberry Crumb Cake. A buttery and moist sour cream coffee cake, full of fresh blueberries and topped with a delicious brown sugar cinnamon crumb topping.

Good thing I like to share ;)

Blueberry Crumb Cake. A buttery and moist sour cream coffee cake, full of fresh blueberries and topped with a delicious brown sugar cinnamon crumb topping.

Blueberry Crumb Cake

Yield: 9 " round cake, 8-12 servings

Ingredients

For the crumb topping:

  • 3/4 cup all purpose flour
  • 1/2 cup brown sugar
  • 1 teaspoon ground cinnamon
  • 1/8 teaspoon salt
  • 4 Tablespoons melted unsalted butter

For the cake:

  • 2 cups all purpose flour
  • 2 teaspoons baking powder
  • 1/2 teaspoon salt
  • 1 cup granulated white sugar
  • zest of one lemon
  • 8 Tablespoons 1 stick unsalted butter, room temperature
  • 2 large eggs, room temperature
  • 3/4 cup sour cream, room temperature (I used light sour cream)
  • 1/4 cup milk, room temperature (I used 1%)
  • 2 cups fresh blueberries, mine was heaping
  • 1 Tablespoon all purpose flour

Optional Toppings:

  • Confectioner's sugar
  • Lemon icing, see notes

Instructions

  1. Preheat oven to 350 degrees F. Spray a 9" round springform pan with cooking spray, or lightly grease bottom and sides. Set aside.
  2. Make the crumb topping. Mix the flour, brown sugar, cinnamon and salt together until fully combined. Add the melted butter and stir until fully incorporated. This will take a minute or two with a spoon, or you can use your hands to work it in more quickly.
  3. Once the mixture is fully combined, pat it down in the bowl with your hands or the back of a spoon so that it is tightly packed in the bowl. Place the bowl in the refrigerator while you mix up the cake batter.
  4. Make the cake. In a medium bowl, whisk together the flour, baking powder and salt. Set aside.
  5. In a large bowl, using a hand held electric mixer or the paddle attachment in a stand mixer, beat the butter, sugar and lemon zest for about 2 minutes until fully combined and fluffy.
  6. Add eggs, one at a time, mixing until combined after each addition.
  7. Whisk the milk and sour cream together in a liquid measuring cup. If they're still cool, you can microwave the mixture for 10 seconds to take any chill off. Just don't allow it to get warm at all.
  8. Add the sour cream/milk mixture to the butter mixture and beat until combined, scraping the sides and bottom of bowl as necessary throughout the entire mixing process.
  9. Gradually add the flour mixture and mix until fully combined. Do not over mix at this stage.
  10. In a separate bowl, toss the blueberries with the flour until they are coated. (Tossing them in flour is optional. See notes)
  11. Carefully fold them into the batter until well distributed being careful not to crush the berries in the process.
  12. Spread batter evenly into prepared pan.
  13. Remove crumb mixture from refrigerator and break up into various sized crumbs. Scatter evenly over cake batter.
  14. With a flat hand, lightly press the crumbs into the batter. We're not trying to compress the batter, we're just giving them a little help to stick to the top.
  15. Bake for 35-40 minutes or until a toothpick inserted into center comes out with just a few moist crumbs. I covered my cake with a piece of foil for the last 10-15 minutes or so of baking time to prevent the crumbs from over browning. Take care not to over bake or you'll risk a dry cake.
  16. Remove from oven and allow to cool for 15 minutes on a cooling rack. Remove sides of the spring form pan and allow cake to finish cooling on the rack. (I opted to remove the bottom of the pan as well and finish cooling on the rack, but it's not necessary.)

Notes

*Instead of, (or in addition to) the sprinkle of confectioner's sugar on top, you can make a lemon icing to drizzle over the cake. To make the icing, mix 1 cup confectioner's sugar with lemon juice (from the lemon you've already zested from the recipe) and a splash of vanilla extract until desired drizzling consistency. It won't take a lot of juice to make the icing. Start by adding a couple of teaspoons of the juice, and then continue to add until you get the thickness you want. I think a thicker consistency is best so that it doesn't get lost amongst the crumbs.

*If you don't have a springform pan, you can bake this in a regular pan, just insure you use one deep enough to hold the batter. I think 3" is best.

*I find it takes too long to allow sour cream and milk to come completely to room temperature by themselves. For this recipe, I whisk the two together and allow to sit at room temperature for 30 minutes. Then, I use the microwave to take the chill off for about 10 seconds. Stir, then check. If the mixture is still cool, I'll give it another 10 seconds or just enough to bring it to room temperature. If it's cold, it will resolidify the butter in the cake batter. If it's warm it will melt the butter. You can just use the microwave to bring the mixture to temperature, but I prefer to take it out of the refrigerator for a bit to give it a head start. See blog post for more tips on speeding up the process of getting your ingredients to room temperature.

*It's not mandatory to toss the berries in flour. I did this step to reduce the risk of the berries sinking, though many claim it's not worth it and you'll get the same results if you skip this step. I don't use the flour method when I make muffins, but was concerned about what would happen in an entire cake. It only takes a few seconds, so I did it. It's your choice.

The Merchant Baker Copyright © 2017

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Karly

Thursday 17th of August 2017

Woah, does this look amazing. LOOOOVE a good crumb cake, and in the summertime I'm always looking for a way to use those perfect blueberries! Yum!

Ramona

Friday 18th of August 2017

Thanks, Karly!

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