01 - Preheat oven to 350°F. Grease and flour two 8-inch round cake pans, lining the bottoms with parchment paper for easy removal.
02 - In a large mixing bowl, sift together the flour, sugar, cocoa powder, baking powder, baking soda, and salt. Whisk to ensure even distribution.
03 - Add eggs, milk, vegetable oil, and vanilla extract to the dry mixture. Beat on medium speed with an electric mixer until smooth and well combined, about 2 minutes.
04 - Carefully pour in the boiling water while mixing on low speed. The batter will become thin and glossy—this is normal for achieving the desired moist texture.
05 - Divide batter evenly between prepared pans. Bake for 30–35 minutes until a toothpick inserted in the center comes out clean or with moist crumbs.
06 - Let cakes cool in pans for 10 minutes, then invert onto wire racks to cool completely before frosting.
07 - Beat softened butter in a large bowl until creamy and pale. Gradually sift in powdered sugar and cocoa powder, mixing on low speed to incorporate.
08 - Add vanilla extract and salt. Beat in milk one tablespoon at a time until frosting reaches smooth, spreadable consistency.
09 - Place one cooled cake layer on a serving plate. Spread a generous layer of frosting over the top. Position second layer on top, then frost the top and sides evenly.
10 - Smooth frosting with an offset spatula. Decorate as desired. Slice and serve immediately or refrigerate for later serving.