In a large bowl, whisk together the flour, cocoa, baking powder, soda and salt. In the bowl of your electric mixer (fitted with the paddle), add the butter and beat until creamy and smooth. Add in the sugar and beat on medium speed until fluffy, scraping down the sides when needed, about 3 to 4 minutes. Beat in the eggs one at a time, mixing for a minute or so and scraping the sides and bottom of the bowl after each. Beat in the vanilla extract.