Blueberry Crumb Cake

Servings 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

Preheat oven to 350 degrees F. Spray a 9" round springform pan with cooking spray, or lightly grease bottom and sides. Set aside.
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.
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.
Make the cake. In a medium bowl, whisk together the flour, baking powder and salt. Set aside.
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.
Add eggs, one at a time, mixing until combined after each addition.
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.
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.
Gradually add the flour mixture and mix until fully combined. Do not over mix at this stage.
In a separate bowl, toss the blueberries with the flour until they are coated. (Tossing them in flour is optional. See notes)
Carefully fold them into the batter until well distributed being careful not to crush the berries in the process.
Spread batter evenly into prepared pan.
Remove crumb mixture from refrigerator and break up into various sized crumbs. Scatter evenly over cake batter.
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.
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.
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.)

Recipe 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.