Preheat your oven to 350°F.
Grease and flour three 8-inch round cake pans. Line the bottom of each pan with parchment paper.
Cream together the butter and sugar in a large mixing bowl until light and fluffy.
Add the eggs and vanilla into the bowl, mixing thoroughly to combine them into the creamed butter mixture.
Whisk the flour, baking soda, baking powder, and salt in a separate bowl.
Dissolve the cocoa powder in boiling water in a medium bowl, stirring until smooth and fully incorporated.
Alternate adding the dry ingredients and the cocoa mixture to the creamed butter. Mix on low speed to gently combine without overmixing.
Divide the batter evenly among the prepared cake pans and smooth out the tops.
Bake the cake layers in the preheated oven for 22 to 28 minutes or until a toothpick comes out clean from the center of each cake.
Allow the cakes to cool in their pans for 10 minutes, then transfer them to a wire rack to cool completely for another 10 to 15 minutes.
Assemble the cake by placing the first layer top-side down on a cake plate and evenly spreading a third of your chosen frosting over it.
Level the top of the second layer, then place it top-side down on the first layer, adding more frosting and spreading it evenly.
Repeat the leveling and frosting with the third layer, then apply the remaining frosting on top for a smooth finish.
Slice and enjoy the cake!