This one’s actually a white cake with chocolate chips, fairly straightforward all ’round, with a little brown sugar and buttermilk to give it an unexpected depth of flavor. The frosting is superthick and sweet. Follow the instructions carefully. It’s sort of like a layer of candy on top of the cake, a coconut-free riff on the stuff used between the layers of a traditional German chocolate cake.
For the cake
16 tablespoons (2 sticks) cool unsalted butter, cut into small chunks, plus additional for the sheet pan
3½ cups all-purpose flour, plus additional for the sheet pan
1 teaspoon baking powder
1 teaspoon baking soda
1 teaspoon salt
18 ounces semisweet or bittersweet chocolate chips
1 cup packed dark brown sugar
1 cup granulated white sugar
2 large eggs plus 2 large egg yolks
1 tablespoon vanilla extract
2 cups regular cultured buttermilk
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. Whisk 3 cups of the flour, the baking powder, baking soda, and salt in a medium bowl until uniform. Toss the remaining ½ cup flour with the chocolate chips in a small bowl.
3. 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 creamy, light, and fluffy, about 5 minutes. Beat in the eggs one at a time, then beat in the egg yolks one at a time, followed by the vanilla.
4. Turn off the mixer and pour the flour mixture evenly on top of the batter. Beat at low speed while slowly pouring in the buttermilk; continue beating until there are no bits of dry flour in the batter.
5. Scrape down and remove the beaters or paddle. Using a silicone spatula, fold in the coated chocolate chips and any residual flour in the bowl until well distributed. Using an offset spatula, scrape and spread the batter evenly into the prepared pan.
6. Bake until firm and set, and until a toothpick or cake tester inserted into the center of the cake comes out clean, 28 to 30 minutes. Cool in the pan on a wire rack until room temperature, about 2 hours.
For the frosting
2¼ cups granulated white sugar
20 tablespoons (2½ sticks) unsalted butter, cut into small chunks
1¼ cups evaporated whole milk (a little less than a 12-ounce can)
9 large egg yolks, at room temperature
2 tablespoons vanilla extract
¼ teaspoon salt
1¾ pounds pecan pieces (about 6 cups)
1. Whisk the sugar, butter, evaporated milk, egg yolks, vanilla, and salt in a medium saucepan set over medium heat until the butter melts. Continue cooking, whisking frequently, until bubbling. Then continue cooking, whisking nonstop, until thick and lightly caramel colored, about 10 minutes.
2. Stir in the pecan pieces and set aside for 2 minutes, stirring occasionally, until somewhat cool but still spreadable. Mound the mixture down the center of the cooled cake, then use an offset spatula to spread it into an even layer.
TESTER NOTES
Cool the frosting just until it won’t singe the cake. But take care: if it gets too cool, you won’t be able to spread it.
