01 - Preheat oven to 350°F. Generously grease and line two 8-inch round cake pans with parchment paper.
02 - Sift flour, sugar, cocoa powder, baking powder, baking soda, and salt into a large mixing bowl. Whisk to ensure even distribution.
03 - Add eggs, milk, vegetable oil, and vanilla extract to the dry mixture. Beat on medium speed until completely smooth and thoroughly combined.
04 - Carefully pour in boiling water while mixing continuously. Blend until batter achieves a glossy, thin consistency.
05 - Divide batter evenly between prepared pans. Bake for 30-35 minutes until a toothpick inserted in the center emerges clean.
06 - Let cakes rest in pans for 10 minutes. Invert onto wire racks and allow to cool entirely before frosting.
07 - Cream butter until light and fluffy. Gradually sift in powdered sugar and cocoa powder, beating until fully incorporated.
08 - Blend in vanilla extract and salt. Add milk one tablespoon at a time, mixing until silky and spreadable.
09 - Position first cake layer on serving plate. Spread frosting evenly over surface. Top with second layer.
10 - Coat top and sides with remaining frosting. Smooth exterior with spatula. Decorate as preferred. Slice and serve.