1 ¼cupsunsalted butter2 ½ sticks, room temperature
5cupspowdered sugar
¼teaspoonsalt
2teaspoonsvanilla extract
zest of half a lemon
⅓cupheavy creamgive or take a few tablespoons
2 - 3tablespoonsblueberry jamI made mine, but you can use store bought
Instructions
Grease and flour two 8-inch round cake pans at least 3 inches high. Preheat the oven to 350 degrees F.
In a bowl, mix together the flours, baking powder, baking soda, and salt together. Set aside.
Beat the butter, sugar, and lemon zest together until light and fluffy. Add the eggs and vanilla, beating well between each addition of the egg.
Alternate between adding the flour (in three additiona) and the buttermilk (in two additions). Begin and end with the flour. Do not overmix!
Gently toss the blueberries with some flour, then fold into the cake batter.
Evenly divide the batter among the cake pans and bake until an inserted toothpicks comes out clean - roughly 45 - 50 minutes (do not worry if it takes you a bit longer than this for the cake to bake through, I find it can be a bit temperamental with baking times)
Allow the cake to cool for about 15 minutes in the pans, then turn out onto wire racks to cool completely. I like to chill the cakes overnight.
Trim the top of the cake so it is level as needed. Cut the cakes in half so you have four round layers.
For the buttercream, beat the butter until soft and creamy. Add in the powdered sugar one cup at a time, beating well until combined. Add in the salt, extract,and zest then mix well. Add in the heavy cream a tablespoon at a time until the buttercream is smooth. Remove a portion of the frosting and place in a piping bag. Remove a third of the remaining buttercream and mix in the blueberry jam one tablespoon at a time until it reaches your desired color.
Pipe a ring around the outer tops of three of the layers. Fill with lemon curd. Place the layers on top of one another, putting the naked layer on the top. Frost the cake with a small portion of the buttercream to create your crumb coat. Place the cake in the refrigerator for about 30 minutes for the crumb coat to set.
Place the regular frosting on the top of the cake, and the blueberry buttercream around the botom half of the cake. Smooth out the frosting so it is an even layer over the cake. The white and blue frosting will intermingle in the middle to create the ombre effect.