1-First, preheat the oven to 350°F (175°C) and prepare one or two cake pans by spraying with oil and lining the bottom with parchment paper. In a large bowl, whisk together all wet ingredients except the coffee or boiling water, including 1 cup milk, 1 cup white sugar, ¾ cup brown sugar, 3 large eggs, 1 teaspoon vinegar, 1 tablespoon vanilla extract, and ⅔ cup oil.

2-Gradually whisk in the sifted dry ingredients until combined, which are 2 ⅔ cups gluten free all-purpose flour with xanthan gum, 1 cup sifted cocoa powder, 1 ½ teaspoons baking powder, 1 teaspoon baking soda, and ½ teaspoon salt. Add 1 cup hot brewed coffee or boiling water and whisk until smooth; the batter will be thin, but that’s normal for a rich texture.

3-Pour the batter evenly into the prepared pan or pans. Bake for 35-45 minutes for a sheet cake or 32-37 minutes for a layer cake, or until a toothpick inserted in the center comes out clean. Let the cake cool in the pan for 10-20 minutes, then invert it onto a cooling rack, remove the parchment paper, and set it upright to cool completely before frosting.

4-For the buttercream, beat ¾ cup softened butter until smooth, then mix in ½ cup sifted cocoa powder. Gradually add 3-5 cups sifted powdered sugar until you reach the desired consistency, and stir in 2-4 tablespoons milk and 2 teaspoons vanilla extract. Frost the cooled cake and decorate as desired for a professional touch.