- 1 cup unbleached all-purpose flour
- ½ teaspoon baking powder
- ½ teaspoon baking soda
- ¼ teaspoon salt
- ¼ cup (½ stick) unsalted butter, at room temperature
- ¾ cup sugar
- 2 large eggs
- 1 teaspoon vanilla extract
- 2 teaspoons grated lemon zest
- 1 tablespoon poppy seeds
- ½ cup buttermilk (any fat content)
- 1 cup heavy whipping cream
- 2 tablespoons powdered sugar
- ½ teaspoon vanilla extract
- ¾ cup plus 2 tablespoons Lemon Filling, cold
- Powdered sugar for dusting
- Make the cupcakes. Position a rack in the middle of the oven. Preheat the oven to 350°F. Line 12 muffin tin cups with paper cupcake liners.
- Sift the flour, baking powder, baking soda, and salt into a medium bowl and set aside. In a large bowl, using an electric mixer on medium speed, beat the butter and sugar until smoothly blended and lightened in color, about 1 minute. Stop the mixer and scrape the sides of the bowl as needed during mixing. Add the eggs one at a time, beating until each is blended and the batter looks creamy, about 1 minute. Mix in the vanilla, lemon zest, and poppy seeds. On low speed, add half of the flour mixture, mixing just to incorporate it. Mix in the buttermilk to blend it. Mix in the remaining flour mixture until it is incorporated and the batter looks smooth.
- Fill each paper liner with a scant ¼ cup (about 3½ tablespoons) of batter, to about ½ inch below the top of the liner. Bake just until the tops feel firm and a toothpick inserted in the center comes out clean, about 18 minutes. The cupcakes will rise just above the tops of the paper liners. Cool the cupcakes for 10 minutes in the pan on a wire rack. Carefully place the wire rack on top of the cupcakes in their pan. Protecting your hands with pot holders and holding the pan and rack together, invert them to release the cupcakes onto the wire rack.
- Make the filling. In a large bowl, using an electric mixer on medium-high speed, beat the cream, powdered sugar, and vanilla until firm peaks form. Using a rubber spatula, fold in ¼ cup of the lemon filling, then swirl in 1½ cup of the remaining sauce, leaving streaks of yellow sauce.
- Use a sharp knife to slice the top (about a ¼-inch-thick slice) off each cupcake. Dust the tops with powdered sugar, and set aside. Leaving a ¼-inch plain edge on each cupcake bottom, use a spoon to mound about ¼ cup filling on each. Cut the tops in half and press them into the filling, the cut sides facing out and the powdered sugar side up; tilt the halves up slightly so that they look like spread wings.
- Spoon the remaining 2 tablespoons lemon filling into a small self-sealing plastic freezer bag. Press out the excess air and seal the bag. Cut off one corner of the bag to make a hole about 1/8 inch long. Hold the bag above the space between each set of wings and squeeze a thin line of lemon filling between the wings. Serve, or cover and refrigerate to serve cold.
- The cupcakes can be refrigerated for up to 2 days.