Preheat oven to 350°F. Grease and flour two 9-inch cake pans.
Add the flour, sugar, cocoa, baking powder, baking soda, and salt to a large bowl or stand mixer. Whisk until combined.
Heat water to a boil on the stove.
Add the milk, oil, eggs, and vanilla to the dry ingredients. Beat until combined. Then slowly pour in boiling water while mixing.
Distribute batter into cake pans. Bake 30-35 minutes or until a toothpick comes out clean. Let cool.
Gather the frosting ingredients. Beat the butter until fluffy and then add in the milk and vanilla. Beat in the sugar a cup at a time and add in the cocoa powder. Beat until it's smooth and all incorporated.
Assemble our cake! Put a layer of frosting on the first cake, place the next cake on top and cover the whole cake in frosting. Enjoy!