Vanilla Cupcakes with Raspberry Curd

To make the cupcakes, preheat an oven to 350°F (180°C). Line 12 standard muffin cups with paper liners.

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

In the bowl of an electric mixer fitted with the whisk attachment, beat together the egg whites and 1 cup (8 oz./250 g) of the granulated sugar on medium-high speed until soft peaks form, about 4 minutes. Transfer the egg whites to another bowl. Set aside.

In the clean bowl of the electric mixer fitted with the flat beater, beat together the butter and the remaining 1 cup (8 oz./250 g) granulated sugar on medium speed until light and fluffy, about 2 minutes. Add the whole egg and vanilla and beat until combined, about 1 minute. Stop the mixer and scrape down the sides of the bowl. With the mixer on low speed, add the flour mixture in 3 additions, alternating with the buttermilk and beginning and ending with the flour, and beat until combined. Stop the mixer and scrape down the sides of the bowl. Increase the speed to high and beat for 20 seconds. Remove the bowl from the mixer.

Using a rubber spatula, gently fold the egg whites into the butter mixture until completely incorporated, taking care not to deflate the peaks.

Divide the batter among the prepared muffin cups, filling them to the edges of the paper liners (you will have some batter left over for the second batch of cupcakes). Bake until a toothpick inserted into the center of the cupcakes comes out clean, about 20 minutes. Transfer the pan to a wire rack and let cool for 5 minutes, then transfer the cupcakes to the rack and let cool completely. Repeat with the remaining batter.

Meanwhile, make the raspberry curd: In a saucepan over medium heat, melt the butter. Add the raspberries, granulated sugar and lemon juice and bring to a simmer, crushing the berries with a whisk as you go. Whisk in the egg yolks, cornstarch and salt and cook, stirring frequently, until the mixture has thickened enough to thoroughly coat the back of a spoon, 8 to 10 minutes.

Strain the raspberry curd through a fine-mesh sieve into a heatproof bowl; discard the seeds. Whisk the curd, then press a piece of plastic wrap directly on the surface and refrigerate until completely cooled. Let stand at room temperature for about 20 minutes before using.

To make the buttercream, in the clean bowl of the electric mixer fitted with the clean flat beater, beat the butter on medium speed until smooth, about 3 minutes. Add the confectioners’ sugar in 3 additions, beating well after each addition. Add the vanilla and salt, increase the speed to medium-high and beat until combined, about 1 minute, stopping the mixer to scrape down the sides of the bowl as needed. Add the cream and beat until combined.

Transfer the buttercream to a large piping bag fitted with a 1/2-inch (12-mm) round piping tip. Pipe the buttercream on the cooled cupcakes, then top each with a dollop of the raspberry curd. Top each cupcake with a cookie and sprinkle with the sanding sugar. Makes 18 cupcakes.

Williams Sonoma Test Kitchen