Preheat oven to 350°F
Line a half sheet pan with parchment paper and lightly spray with nonstick spray
In a small bowl, whisk together all dry ingredients
In a large bowl, mix all wet ingredients until smooth
Add dry ingredients to the wet and whisk until just combined
Carefully pour in the hot coffee and mix slowly until batter is smooth and uniform
Pour into prepared pan and bake for 12–18 minutes, or until the cake springs back when gently touched or a toothpick comes out clean
While the cake bakes and cools, prepare the buttercream by mixing all ingredients in a stand mixer (or use a hand mixer or whisk) until light and fluffy
Once the cake is fully cooled, spread with chocolate buttercream
Serve as a single layer sheet cake or stack for a layered version
