Preheat your oven to 350 degrees.

Grease two - 9 inch cake pans.

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

In the bowl of your stand mixer using the paddle attachment cream together the butter and sugar for about 3 minutes until creamy. Add the eggs whites and vanilla. Beat until you have a smooth batter.

Add the flour mixture, milk and sour cream and beat until combined. 

Divide the batter evenly between your pans. 

Bake at 350 degrees for 22-25 minutes. The cakes will be golden brown and spring back slightly when touched. You can test with a tooth pick to see if it comes out clean.

Let the cakes cool for 10 minutes in the pans and then flip onto a cooling rack. Let the cakes cool completely before frosting them.

For the frosting I use my recipe for Easy Vanilla Buttercream Frosting.

For the filling I use my recipe for Gluten Free Lemon Curd.