We decided to top this straightforward cake with an autumnal extravaganza, a frosting that’s rich and flavorful, a great way to end a meal anytime between Columbus Day and Thanksgiving. The technique for the cake batter is a little different: you add the flour just at the end, then the melted butter to help incorporate that flour.
For the cake
12 tablespoons (1½ sticks) unsalted butter, melted and cooled, plus additional for the sheet pan
1½ cups cake flour, plus additional for the sheet pan
10 large eggs, at room temperature
1½ cups packed dark brown sugar
4½ teaspoons vanilla extract
½ teaspoon salt
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.
2. Using a handheld electric mixer or a stand mixer with the whisk attachment, beat the eggs and brown sugar in a large bowl at medium speed until doubled in volume, about 8 minutes. Beat in the vanilla and salt.
3. Scrape down and remove the beaters or paddle. Also scrape down the inside of the bowl. Sprinkle the flour over the batter. Using a silicone spatula, fold in the flour in wide, slow, even strokes until there are no undissolved specks.
4. Add the melted butter; fold gently until uniform. Use an offset spatula to spread the batter evenly into the prepared pan.
5. Bake until firm and lightly browned, and until a toothpick or cake tester inserted into the center of the cake comes out clean, 16 to 18 minutes. Cool in the pan on a wire rack to room temperature, about 1½ hours.
For the buttercream
10 tablespoons (1¼ sticks) unsalted butter, softened to room temperature
10 ounces full-fat cream cheese, softened to room temperature
¼ cup canned solid pack pumpkin
1 tablespoon vanilla extract
½ teaspoon ground cinnamon
¼ teaspoon freshly grated nutmeg
¼ teaspoon salt
4 to 5 cups confectioners’ sugar
Up to ½ cup unsalted pumpkin seeds (aka pepitas), for topping
1. Using a handheld electric mixer or a stand mixer with the whisk attachment, beat the butter and cream cheese in a large bowl at medium speed until smooth, about 2 minutes. Add the pumpkin, vanilla, cinnamon, nutmeg, and salt; beat until smooth, about 1 minute.
2. Turn off the mixer, add 4 cups of the confectioners’ sugar, and beat at low speed until smooth. Continue beating at low speed, adding more confectioners’ sugar in ¼-cup increments, until the frosting will hold its shape. Using an offset spatula, spread and smooth the frosting over the cooled cake. Garnish the top with pumpkin seeds before serving.
