White Chocolate Cupcakes with Truffle Filling

Preheat the oven to 325°F (160°C). Place paper liners in the wells of the Muffin Pan. Whisk the flour and baking powder in the Small Batter Bowl. Combine the milk and vanilla in a (1-cup/250-mL) Easy Read Measuring Cup. In the Stainless Steel (2-qt./2-L) Mixing Bowl, beat the egg whites on the high speed of an electric mixer until stiff peaks form. In the Stainless (4-qt./4-L) Mixing Bowl, beat the butter and granulated sugar on medium-high speed until the mixture is fluffy; beat in the sour cream until smooth. On medium speed, add the flour mixture in three parts, alternating with the milk mixture, and mixing until smooth. Whisk in one-third of the egg whites with a Stainless Whisk. Fold in the remaining egg whites using the whisk. Using the Large Scoop, divide the batter evenly among the liners.

Bake for 17–20 minutes or until a wooden pick inserted in the cupcake centers comes out clean. Remove the pan from the oven to a Stackable Cooling Rack. Immediately snip a ½"-deep (1-cm) “x” into top of each cupcake using the Professional Shears. Press one truffle into each cupcake until the truffle is just below the surface of the cupcake top. Remove the cupcakes from the pan. Cool for 30 minutes or to room temperature. The truffles will melt into the cupcakes.

For the frosting, place the white chocolate into the Small Micro-Cooker^®. Microwave, uncovered, on HIGH for 1–1½ minutes or until the chocolate is mostly melted, stirring every 30 seconds. Let the chocolate stand for 3 minutes or until it's slightly cooled. In a clean Stainless Steel (4-qt./4-L) Mixing Bowl, combine the melted chocolate, cream cheese, butter, and vanilla. Using clean beaters, beat the frosting on medium speed until well blended. Slowly add the powdered sugar and beat well.

Place the frosting in the small decorating bag fitted with closed star tip. Pipe the frosting evenly around the tops of the cupcakes. Garnish the cupcakes with chocolate curls, if desired.