Chocolate Texas Sheet Cake with Peanut Butter Frosting
Author: 
Yield: 1 half sheet cake • about 24 servings
 
Ingredients
For the Chocolate Sheet Cake
  • 2 cups (255 g) all-purpose flour
  • 1 1⁄4 cups (250 g) granulated sugar
  • 1 cup (220 g) firmly packed light brown sugar
  • 3⁄4 teaspoon kosher salt
  • 2 large eggs
  • 1 large egg yolk
  • 1⁄2 cup (120 ml) well-shaken buttermilk
  • 1 tablespoon pure vanilla extract
  • 6 ounces (11⁄2 sticks/170 g) unsalted butter, cut into 1-inch (2.5-cm) pieces
  • 1 cup (240 ml) coffee
  • 1⁄3 cup plus 1 tablespoon (35 g) unsweetened cocoa powder
  • 1⁄4 cup (50 g) vegetable shortening
  • 1 teaspoon baking soda
For the Peanut Butter Frosting
  • 14 ounces (395 g) confectioners’ sugar (about 4 cups)
  • 2⁄3 cup (165 ml) evaporated milk
  • 4 ounces (1 stick/115 g) unsalted butter, cut into small pieces
  • 1⁄2 cup (130 g) creamy natural peanut butter
  • 1⁄4 teaspoon kosher salt 1 teaspoon pure vanilla extract
  • 1 1⁄2 cups (225 g) salted roasted peanuts, finely chopped
Instructions
Make the Chocolate Sheet Cake
  1. Preheat the oven to 350°F (175°C). Lightly spray a half sheet pan with nonstick cooking spray. Line the pan with parchment paper, then lightly spray the parchment and the sides of the pan. Alternatively, you can grease and lightly flour the parchment paper and the sides of the pan.
  2. In a large bowl, whisk together the flour, both sugars, and the salt. Make a well in the center of the bowl. Set aside.
  3. In a small bowl, whisk together the eggs, egg yolk, buttermilk, and vanilla. Set aside.
  4. In a medium saucepan set over medium heat, stir together the butter, coffee, cocoa powder, shortening, and baking soda. Once the butter just begins to melt, increase the heat to medium-high and bring the mixture to a boil for 20 to 45 seconds, but no more. Pour the hot mixture into the well of the dry ingredients and fold it all together. The mixture should be nearly room temperature (if it is not, wait a few minutes). Add the buttermilk mixture to the chocolate mixture and whisk
  5. gently to combine.
  6. Pour the batter into the prepared pan and place in the oven. Bake the sheet cake until a toothpick
  7. inserted in the center comes out clean, 15 to 18 minutes, rotating the pan halfway through the
  8. baking time. Do not overbake; err on the side of slightly underbaked if you must.
  9. Start making the icing while the cake is baking (the icing must be applied to a hot cake to fuse
  10. properly).
Make the Peanut Butter Frosting
  1. Sift the confectioners’ sugar into a large bowl. (If you want to make sure your frosting is extra smooth, sift the sugar twice.)
  2. In a medium saucepan set over medium heat, stir together the evaporated milk, butter, peanut butter, and salt. Once the butter begins to melt, increase the heat to medium-high and bring the mixture just to a boil.
  3. Pour the hot mixture over the sifted confectioners’ sugar and whisk to combine. Add the vanilla and whisk again for 10 seconds.
  4. Pour the frosting over the hot cake and spread it into a consistent layer with an offset spatula. Sprinkle the chopped peanuts over the frosting and allow the entire cake and frosting to come to room temperature. Place the cake in the refrigerator for about 45 minutes to fully set the frosting.
  5. Slice and serve the cake cold (our preference), or bring it to room temperature first.
Notes
How to store: the cake will keep in an airtight container at room temperature or in the refrigerator for up to 3 days.
Recipe by Baked Sunday Mornings at http://bakedsundaymornings.com/2015/02/16/in-the-oven-chocolate-texas-sheet-cake-with-peanut-butter-frosting/