Preparation Steps

• Preheat the oven to 350°F (175°C). Grease and flour a 13x18-inch rimmed baking sheet or line it with parchment.
• In a large bowl, whisk together the flour, sugar, cocoa powder, baking soda, and salt until evenly combined.
• Add the eggs, buttermilk, vegetable oil, and vanilla to the dry ingredients and mix until smooth and combined.
• Carefully stir in the boiling water until the batter is smooth; the batter will be thin, which yields a moist sheet cake.
• Pour the batter into the prepared sheet pan and spread it evenly with a spatula.
• Bake for 20 to 25 minutes, or until a toothpick inserted in the center comes out with a few moist crumbs. Do not overbake.
• While the cake bakes, prepare the coconut-pecan frosting: combine evaporated milk, sugar, egg yolks, and butter in a medium saucepan.
• Cook the frosting mixture over medium heat, stirring constantly, until it thickens and reaches a gentle boil, about 8 to 10 minutes.
• Remove the pan from heat and stir in the shredded coconut, chopped pecans, and vanilla. Let the frosting cool slightly so it thickens but remains spreadable.
• When the cake is done, remove it from the oven and allow it to cool for 5 to 10 minutes. While still warm, spread the frosting evenly over the cake so it adheres.
• Let the cake cool completely to room temperature before slicing into 12 pieces. Store covered at room temperature for 1–2 days or refrigerate for longer storage.