2hr · 10 servings For the Guinness Chocolate Bundt: nonstick baking spray for the pan 1 cup (199g) granulated sugar 1 cup (213g) light brown sugar packed 2 cups (240g) all-purpose flour 1 cup (84g) unsweetened cocoa powder 2 teaspoons espresso powder 1 teaspoon baking soda 1/2 teaspoon baking powder 1/2 teaspoon salt 5 large eggs room temperature 1 cup (227g) full-fat sour cream room temperature 8 ounces Guiness beer 3/4 cup (170ml) vegetable oil 1/2 cup (113ml) whole milk 2 teaspoons vanilla extract For the Baileys Buttercream: 1 cup (227g) unsalted butter room temperature 2 and 1/2 cups 284g) confectioners' sugar sifted 3 Tablespoons (42ml) Baileys Irish cream liqueur 1 Tablespoon (14ml) whole milk room temperature 1 teaspoon vanilla extract 1/4 teaspoon salt 4