Killer Cupcakes

Preheat oven to 350˚. Line 2 standard muffin tins with cupcake liners; set aside.

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.

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.

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.

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.

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.

Fit a pastry bag with a 3/8-inch plain round tip and fill with butter cream. Pipe butter cream in a circular motion on top of each cupcake; sprinkle with sanding sugar. Pipe a dollop of butter cream in the center of each cupcake and top with a raspberry.

Prepare and ice-water bath. Set a medium bowl in ice-water bath and set aside.

Place sugar and lemon zest in a mortar and grind with a pestle to combine and release the oils. Transfer sugar mixture to a medium heatproof bowl along with eggs and egg yolks; whisk to combine. Place over a saucepan of simmering water and whisk until sugar has dissolved. Add lemon juice and continue whisking until mixture is thick and reaches 160 degrees on an instant-read thermometer, scraping down sides of bowl as necessary. Add butter and whisk until well combined.

Strain lemon mixture through a fine mesh sieve set over prepared bowl. Cover lemon curd with plastic wrap, pressing plastic wrap directly onto surface. Transfer to refrigerator until completely chilled.