Adapted from Baked: New Frontiers in Baking by blogger Shauna Sever, this recipe uses root beer in the cake and frosting. Bake it a day ahead to give the flavors time to fully mellow and mingle, and “don’t even think of using diet root beer,” says Sever. “Not even for a second.”
2 cups root beer (Sever uses cane-sweetened Boylan)
1 cup dark unsweetened cocoa powder (Sever suggests Valrhona)
1/2 cup unsalted butter, cut into pieces
1 1/4 cups granulated sugar
1/2 cup firmly packed dark brown sugar
2 cups all-purpose flour
1 1/4 tsp. baking soda
1 tsp. salt
2 large eggs
2 cups confectioners’ sugar
1/3 cup dark unsweetened cocoa powder
1/4 tsp. salt
1 tsp. pure vanilla extract
1/4 cup root beer
3 Tbsp. unsalted butter, very soft
Position an oven rack to the lower third of the oven and preheat it to 325 degrees F. Spray a 10-inch Bundt pan generously with nonstick cooking spray.
Combine the root beer, cocoa powder and butter in a medium saucepan. Place it over medium heat and warm the mixture, stirring often, until the butter is melted. Whisk in the sugars. Let cool.
In large bowl, sift together the flour, baking soda and salt.
Lightly beat the eggs in a small bowl, then whisk them into the cooled root beer-cocoa mixture. Make a well in the center of the dry ingredients, and gently stir the wet ingredients into the dry. The batter will be slightly lumpy, and this is perfectly fine. Don’t over-mix the batter. Scrape the batter into the prepared pan.
Bake the cake until a toothpick inserted into the cake comes out clean, about 45-50 minutes. Let the cake cool for at least 30 minutes in the pan before gently loosening the sides of the cake from the pan and inverting it onto a wire rack to cool completely (spray the rack lightly with nonstick spray before inverting the cake to prevent it from sticking as it finishes cooling).
To make the glaze, whisk together the confectioners’ sugar, cocoa powder, salt, vanilla and root beer in a medium bowl until fully incorporated. Whisk in the softened butter until smooth. If necessary, adjust the glaze with more confectioners’ sugar to thicken the glaze or a bit of root beet to thin it—you want it to flow lazily off a spoon—not too runny, but nowhere near spread-able. Spoon the glaze over the cake and let it drip down the sides. Let the glaze set for 15 minutes or so before serving. This cake keeps covered at room temperature for at least 5 days, or longer if refrigerated.