Directions

1. Preheat oven to 350 degrees. Line 2 standard muffin tins with cupcake liners; set aside.
2. In the bowl of an electric mixer fitted with the paddle attachment, beat butter and sugar together until light and fluffy. Add vanilla; beat to combine. Add egg yolks, one at a time, beating well after each addition.
3. Sift together both flours, baking powder, and salt into a large bowl. With the mixer on low, add flour mixture; mix until well combined. Add sour cream; mix until well combined.
4. In a clean bowl of an electric mixer fitted with the whisk attachment, beat egg whites until stiff peaks form. Gently fold egg whites into batter.
5. Fill each muffin cup half full with batter. Transfer muffin tins to oven and bake until a skewer inserted into the center of one of the cupcakes comes out clean, 20 to 24 minutes. Let cupcakes cool completely.
6. Using an apple corer, make a hole in the top of each cupcake, taking care not to push the corer through the bottom; remove cake from hole. Fill a squirt bottle with lemon curd and squeeze curd into holes.
7. Fit a pastry bag with a 3/8-inch plain round tip and fill with buttercream. Pipe buttercream in a circular motion on top of each cupcake; sprinkle with sanding sugar. Pipe a dollop of buttercream in the center of each cupcake and top with a raspberry.