• Preheat the oven to 350 degrees. Line 3 - 6” cake pans with parchment paper and spray with baking spray containing flour.
• Set aside. (2- 8” cake pans will also work with this recipe)
• In a small bowl, whisk the flour, baking powder, baking soda and salt together. Set aside.
• In a large bowl, beat the butter, sugar and brown sugar together until light and fluffy, 2-3 minutes of mixing.
• Add in the eggs and vanilla and continue to beat until creamy.
• Alternate adding the flour mixture and the buttermilk, beginning and ending with the flour until all ingredients are thoroughly combined.
• Pour into the cake pans in equal amounts (a small kitchen scale can be helpful in making sure each pan has the same amount.)
• Place the cake pans in the oven and bake for 30-35 minutes, until a skewer or knife comes out cleanly.
• Remove and let cool in the pans for 10 minutes before removing and letting cool on a rack to room temperature.
• To make the pie filling, place the pecans, water, brown sugar, cornstarch and egg yolk in a pan and whisk over low/medium heat until it boils.
• Let cook for 1-2 minutes before removing and adding the butter and vanilla.
• Set aside and let cool completely.
• To make the frosting, place the butter and beat with an electric mixer until it changes to a lighter color, about 2 minutes. Add in the powdered sugar and vanilla and beat until smooth and creamy.

To assemble:

• Trim cakes if domed on top to create a flat surface.
• Place the bottom layer of cake on a cake stand.
• Pipe a circle of the buttercream frosting around the edge of the cake. It doesn’t have to be perfect, it’s just to hold the filling inside the layer.
• Spoon the pecan filling into the center of the frosting and spread in an even layer. Do not overfill the layer or the cake will end up lopsided.
• Place the next layer of cake and repeat with the frosting and pecan filling.
• Once the layers are stacked, start by creating a thin layer of frosting over the entire cake.
• Place the cake in the fridge to set the frosting for about 30 minutes.
• Remove and add more frosting to create a smooth finish.
• Pipe extra swirls on top and place pecans on top of each peak (if desired).
• Slice and enjoy!