LEMONADE CAKE WITH LEMON CURD WHIPPED CREAM
We feel the best lemon cakes are made with lemonade, a concentrated jolt of flavor that gives the cake a particularly summery stripe (even in winter). Make sure you use regular lemonade concentrate, not low-sugar or sugar-free. The frosting here is simple but gorgeously sophisticated: lemon curd folded into whipped cream. (See the Tester Note below for a shortcut.)
For the lemon curd
2 teaspoons finely grated lemon zest plus ½ cup fresh lemon juice
½ cup granulated white sugar
3 large eggs, at room temperature
6 tablespoons (¾ stick) unsalted butter, cut into small bits
1. Set up a double boiler or a heat-safe bowl that fits snugly over a medium saucepan with about 1 inch of slowly simmering water. Whisk the lemon juice and sugar in the top half of the double boiler or the bowl for a few seconds, then whisk in the eggs, butter, and lemon zest. Continue whisking—do not stop—until thick and rich, about 12 minutes. Scrape into a medium bowl and refrigerate for at least 4 hours or overnight.
For the cake
9 tablespoons (1 stick plus 1 tablespoon) cool unsalted butter, cut into chunks, plus additional for the sheet pan
3 cups cake flour, plus additional for the sheet pan
½ teaspoon baking soda
½ teaspoon salt
1½ cups granulated white sugar
1 tablespoon finely grated lemon zest
3 large eggs plus 3 large egg whites, at room temperature
5 tablespoons frozen lemonade concentrate, thawed
2 teaspoons vanilla extract
2 teaspoons lemon extract
1. Position the rack in the center of the oven. Heat the oven to 350°F. Generously butter and lightly flour the inside of a 13 × 18-inch lipped sheet pan. Whisk the flour, baking soda, and salt in a medium bowl until uniform.
2. Using a handheld electric mixer or a stand mixer with the paddle attachment, beat the sugar, butter, and lemon zest in a large bowl at medium speed until creamy, light, and fluffy, about 5 minutes. Scrape down the inside of the bowl, then beat in the eggs one at a time, followed by the egg whites one at a time.
3. Beat in the lemonade concentrate, vanilla, and lemon extract until smooth. Turn off the mixer; pour the flour mixture over the top of the batter. Beat at medium speed to create a very thick batter. Using an offset spatula, spread the somewhat stiff batter evenly into the prepared pan.
4. Bake until pale beige and set, and until a toothpick or cake tester inserted into the center of the cake comes out clean, 18 to 20 minutes. Cool in the pan on a wire rack to room temperature, about 1½ hours.
For the whipped cream
1½ cups heavy cream
¾ cup confectioners’ sugar
¼ teaspoon salt
1. Using a handheld electric mixer or a stand mixer with the whisk attachment, beat the cream, confectioners’ sugar, and salt in a large bowl at high speed until you can make soft peaks. Scrape down and remove the beaters or whisk.
2. Using a silicone spatula, fold in the lemon curd until uniform. Use that same spatula to spoon and spread the whipped cream mixture evenly over the cooled cake.
TESTER NOTES
You can substitute purchased lemon curd for the homemade. Skip step 1 and use 2 cups (about two 10-ounce jars). If possible, use a bottled lemon curd that includes lots of real butter for the best flavor. Notice, too, that this whipped cream is sweeter than the one used for the Strawberry Shortcake. Here, we want a bigger contrast to the tart lemon flavor.