Blueberry cake layers with vanilla buttercream, blueberry compote, and cobbler crunch filling.
HEAT THE OVEN: Preheat your oven to 325 degrees. Spray three 8-inch round pans with nonstick spray, line the bottom of each pan with parchment paper and spray again. Set aside.
MAKE THE PUREE: In a medium saucepan, cook the blueberries over medium-low heat until the berries soften. Transfer berries to a blender or food processor and pulse until smooth. Should make 1 cup puree. Set aside.
MIX THE INGREDIENTS: In a medium bowl whisk together the cake flour, baking powder, and salt. Set aside.
In a bowl of a stand mixer fitted with a paddle attachment, beat the butter and sugar together on medium-high for about 2 to 3 minutes, until lighter in color.
With the mixer in medium speed, add the egg whites and egg, one at a time. Make sure to scrape down the sides and bottom of the bowl between additions. Once all of the eggs are added, turn the mixer to medium-high and beat for an additional 2 minutes.
Stir in the vanilla extract and blueberry emulsion.
With the mixer on low, alternately add the dry ingredients with the blueberry puree in three additions, starting and finishing with the dry ingredients.
NOTE: I left my batter naturally colored by the emulsion and puree. For more of a purple or blue, use a drop of food coloring.
BAKE THE CAKE: Evenly divide the batter between the three pans (about 15 ounces of batter in each) and bake for about 25 to 30 minutes, or until a toothpick inserted in the center of the cake comes out with a few moist crumbs on it.
Let the cake layers cool on racks for 10 minutes before inverting onto greased wire racks to cool completely.
MIX THE INGREDIENTS: Combine all of the ingredients in a medium saucepan over medium heat. Bring to a soft boil and cook for 5 minutes, stirring occasionally. You want the blueberries to burst and the liquid to thicken. It should coat your spoon well.
This is best made a day or two ahead of time. Store in an airtight container in the refrigerator.
BEAT THE BUTTER: In the bowl of a stand mixer fitted with a paddle attachment, beat the butter for about 2 minutes.
MIX THE INGREDIENTS: With the mixer on low, gradually add the sifted powdered sugar, one cup at a time, mixing a little in between each addition.
With mixer on medium speed, add whipping cream, vanilla bean and salt.
Turn the mixer to medium-high speed and beat for an additional 3 to 5 minutes. The buttercream will become lighter in color and texture.
Before spreading on your cake, spend a couple minutes mixing the buttercream by hand with a wooden spoon to push out the air pockets.
HEAT YOUR OVEN: Preheat your oven to 300 degrees F.
MIX THE INGREDIENTS: Combine the sugars, flour, baking powder, cinnamon, and salt in the bowl of a stand mixer fitted with the paddle attachment. Mix on low until combined.
Add the oil and the vanilla and beat on low until the dry ingredients are "wet."
Spread the crumbs on a baking sheet lined with parchment paper. Use your hands to clump some of the pieces together to make larger chunks.
BAKE THE CRUMBS: Bake the crumbs for about 15 minutes and then let cool completely before using.
STACK THE LAYERS: Place the first cake layer, top side up, in the center of a cake board or cake plate.
Evenly 1/2 cup of buttercream over the cake layer and then pipe a rim of buttercream around the edge of the cake.
Gently spread about 1/2 cup of the blueberry compote over the buttercream.
Sprinkle about 1/2 cup of the crumble over the blueberry compote and pat into place.
Repeat these step until you get to the final cake layer, which you will lay top side down.
Apply a thin coat of buttercream around the entire cake to lock in the crumbs. Freeze for about 10 minutes.