Preheat the Oven: Preheat your oven to 350°F (180°C) for a standard oven or 320°F (160°C) for fan/convection ovens. Grease two 9-inch (22 cm) round cake pans with butter, then line the bottom with parchment paper to prevent sticking.
Prepare the Dry Ingredients: In a large bowl, sift together 1 3/4 cups of all-purpose flour, 3/4 cup of unsweetened cocoa powder, 1 1/2 teaspoons of baking powder, 1 1/2 teaspoons of baking soda, and a pinch of salt. Whisk in 2 cups of white granulated sugar to combine the dry ingredients well.
Add the Wet Ingredients: To the dry ingredients, add 2 large eggs, 1 cup of milk, 1/2 cup of vegetable oil, and 2 teaspoons of pure vanilla extract. Use a whisk to mix everything until the batter is smooth and lump-free, about 30 seconds.
Incorporate Boiling Water: Gradually pour 1 cup of boiling water into the batter, mixing well. The batter will be quite thin, but that’s exactly what you want—it results in a moist and fluffy cake.
Bake the Cake: Divide the batter evenly between the prepared cake pans. Bake in the preheated oven for 30-35 minutes, or until a wooden skewer inserted into the center of the cakes comes out clean. Be sure to check the cakes at the 30-minute mark to prevent overbaking.
Cool the Cake: Let the cakes cool in the pans for 10 minutes. Afterward, remove them from the pans and transfer them to wire racks to cool completely before frosting.
Chocolate Buttercream Frosting
Prepare the Frosting: Melt 4 oz of butter in a small saucepan. Once melted, whisk in 2/3 cup of unsweetened cocoa powder until smooth and fully incorporated.
Combine the Sugar and Milk: Alternately add 3 cups of powdered sugar and 1/3 cup of milk, beating after each addition. Continue mixing until the frosting reaches a smooth, spreadable consistency. If the frosting is too thick, you can add a small amount of extra milk to loosen it up.
Finish the Frosting: Stir in 1 teaspoon of vanilla extract to add extra flavor. Your frosting should be creamy and fluffy, perfect for spreading over the cake.
