In a medium bowl, mix water/coffee with cocoa. Set aside.
Preheat oven to 350°
Prepare a 13x9 pan with a baking spray or shortening and a tablespoon or two unsweetened cocoa or flour, for easy release of cake from the pan.
In a large bowl with a mixer beat butter, sugar, eggs, and vanilla.
Add in the flour, baking soda, salt, and baking powder, and with mixer on low pour in the cocoa mixture.
Begin mixing on low, then on medium for about 1 minute to completely mix cake batter together.
Pour cake batter into prepared pan, bake for 35-40 minutes or until a toothpick comes out clean.
Allow cake to cool for 15 minutes, then turn the cake out onto a cooling rack or cool this cake in the pan completely if leaving the cake in the pan and frosting the top of the cake.
Make sure the cake is completely cooled before frosting the cake.