In a medium sauce pan, whisk the pineapple juice and coconut milk together. Heat over medium heat, stirring occasionally until the liquid is hot and steaming, but not boiling. Remove from heat.

While you're waiting for the juice and milk to heat...in a small bowl, whisk the sugar, cornstarch and salt together. Set aside.

In a medium bowl, whisk the yolks and egg until fully combined. Whisk in the sugar/cornstarch/salt mixture until light and fluffy. Using a ladle, slowly add the hot milk mixture to the egg mixture while constantly whisking. Continue adding the hot milk mixture to the egg one ladle at a time, whisking constantly until all of the hot milk has been fully incorporated. 

Pour the egg/milk mixture back into the saucepan over medium heat and whisk constantly until mixture begins to boil. Once it's bubbling, whisk vigorously for 3-4 minutes. Remove from heat and whisk in the butter, a few small pieces at a time.

Pass the mixture through a sieve onto a small baking sheet or cake pan, pressing the cream in the strainer to remove any cooked egg bits. Quickly spread the cream evenly on the cake pan and cover with a layer of plastic wrap, pressing the wrap directly on the surface of the cream so that it doesn't form a skin.

Allow the cream to come to room temperature, then refrigerate until ready to assemble cake.

Preheat oven to 350 degrees F. Spray or grease two 9" round cake pans. Line the bottoms with parchment paper. Lightly spray the parchment paper. Set aside.

In a medium bowl, whisk the flour, baking powder, baking soda and salt. Set aside.

In a large mixing bowl, cream butter and sugar on medium speed for 3-4 minutes or until light and fluffy. Add vanilla and orange zest and mix briefly to distribute. Add eggs one at a time, mixing well and insuring each egg is completely incorporated before adding the next egg.

Alternate adding the flour mixture and buttermilk to the butter mixture, starting and ending with the flour mixture and mixing between each step. You'll add in the oranges when you add the last 1/2 of the buttermilk. In other words, add 1/3 of the flour, 1/2 of buttermilk, 1/3 of the flour, the last 1/2 of buttermilk plus the drained oranges, then the final 1/3 of the flour. You don't have to measure each part exactly, just eye it as you add it. And you don't have to fully mix at each step. For, example, It's okay to have a few streaks of flour left when you go to add the buttermilk. Just make sure you have it fully mixed at the end. You don't want to overwork the batter and risk a tough cake.

Divide batter equally between prepared cake pans spreading batter evenly in each pan. Bake for 30-35 minutes or until top is light golden brown, top springs back when lightly pressed and a toothpick comes out with just a few moist crumbs.

Allow cakes to cool for 10-15 minutes in the pan. Then remove from pans and allow to finish cooling on a rack.

In a large bowl, whip cream and confectioner's sugar until thick but before soft peaks form. Sprinkle gelatin over the cream, add pineapple and beat until mixture has thickened. Take care not to over beat. 

If cakes have domed, cut the tops off to level them so that you'll have even layers to fill. Then, cut each cake layer horizontally in two, to make a total of four layers. Place the bottom layer on your serving dish. 

Remove pineapple coconut pastry cream from the refrigerator. It's going to be well set and fairly firm. Place it into a bowl and whisk it until it's creamy and easy to spread. Take half of the pastry cream and spread it on the bottom cake layer, stopping about 1/2 inch from the edge. Top with another cake layer.

Scoop a generous amount of the pineapple whipped cream onto the next cake layer and spread evenly. You want the whipped cream layer to be a good 1/2 inch thick. Place the third cake layer on top of the whipped cream.

Cover the third cake layer with the last half of the pastry cream, spreading evenly and stopping 1/2" from the edge. Top with the final layer. Check your layers to insure they haven't slid out of place and that your cake is straight.

Cover the top and sides with the remaining whipped cream. When you're covering the sides, make sure to add enough whipped cream to fill in all the gaps between the layers (like spackling) so that you'll have a nice even edge. 

Coat the sides and top with coconut chips if desired. I did not fully coat the top of the cake with coconut, instead choosing to fill the center with flowers. Store cake in the refrigerator for up to 3 days.