Mix butter, and sugar together until light in color.
Add in vanilla extract.
Add in the eggs, one at a time, mixing until just blended in between each egg.
Add cocoa powder, flour, baking powder, and salt.
Stir until well blended. Scrape the sides with a rubber spatula to make sure everything is integrated.
Bale for 30-35 minutes until an inserted toothpick comes out mostly clean.
Allow to cool for 2 hours before adding frosting on top (or place in the fridge for about 45 minutes)