SCOTTISH OAT CAKE WITH SOUR CREAM FROSTING

What do a Scottish oat cake, a cream scone, and an American sheet cake have in common? This recipe! It’s a hybrid among them. The resulting cake is dense, robust, and even a little chewy, thanks to the oats. It gets topped with a light frosting, a combination of whipped cream and sour cream.

For the cake

10½ tablespoons (1 stick plus 2½ tablespoons) cool unsalted butter, cut into small chunks, plus additional for the sheet pan

1 cup whole or 2% milk

1⅓ cups rolled oats

2 cups all-purpose flour

1½ teaspoons baking soda

½ teaspoon salt

1 cup granulated white sugar

1 cup packed light brown sugar

2 large eggs plus 1 large egg white, at room temperature

1 cup regular cultured buttermilk

1. Position the rack in the center of the oven. Heat the oven to 350°F. Generously butter the inside of a 13 × 18-inch lipped sheet pan.

2. Warm the milk in a medium saucepan set over medium heat until small bubbles fizz around the inside perimeter of the pan. Stir in the oats, cover, and set aside for 1 hour.

3. Whisk the flour, baking soda, and salt in a medium bowl until uniform.

4. Using a handheld electric mixer or a stand mixer with the paddle attachment, beat the butter and both sugars in a large bowl at medium speed until light, fluffy, and creamy, about 5 minutes. Scrape down the inside of the bowl and beat in the eggs one at a time.

5. Beat in the egg white until smooth and uniform. Add the oat mixture and beat at low speed until well combined. Scrape down and remove the beaters or paddle.

6. Using a silicone spatula, fold in a third of the flour mixture, then half the buttermilk until smooth. Fold in half the remaining flour mixture, then the remaining buttermilk, just until the flour has dissolved. Finally, fold in the remaining flour mixture just until there are no dry specks of flour in the batter. Using an offset spatula, spread the thick batter evenly into the prepared pan.

7. Bake until lightly browned and set, and until a toothpick or cake tester inserted into the center of the cake comes out clean, about 18 minutes. Cool in the pan on a wire rack to room temperature, about 1½ hours.

For the frosting

2 cups cold heavy cream

1 cup full-fat sour cream

2 teaspoons vanilla extract

2 cups confectioners’ sugar

1. Pour the cream into a large bowl. Using a handheld electric mixer or a stand mixer with the whisk attachment, beat at high speed until you can form stiff peaks, about 2 minutes. Scrape down and remove the beaters or whisk.

2. Whisk the sour cream and vanilla in a second large bowl. Whisk in the confectioners’ sugar until smooth.

3. Using a silicone spatula, fold in the beaten whipped cream without deflating it, until smooth and moundable. Using an offset spatula, spread the frosting over the cooled cake.

TESTER NOTES

Because of the oats, the cake won’t keep well after the first day at room temperature. But it does freeze well before frosting. Once cooled, cut it into quarters or even smaller pieces, wrap them individually, and freeze for up to four months.