Preheat the oven to 350°
Prepare 3, 6-inch round cake pans with a baking spray, and line 6 cupcake portions with paper liners.
In a medium bowl, combine the cocoa and water/coffee and whisk until smooth. Allow this mixture to cool.
In a separate medium bowl, whisk flour with baking soda, salt, and baking powder.
In the bowl of a mixer beat the butter on high until smooth, add in the sugar, and mix on medium to combine, scrape down the sides of the bowl.
Add in the eggs and vanilla and mix on medium-low for a few minutes until nice and smooth.
Add in the cocoa mixture and mix on low to incorporate, then turn to a medium-low speed and mix to combine (don't whip)
Pour the cake batter dividing it into the 3 pans and 6 cupcakes, fill the cake pans 2/3 full, and 3 tablespoons for each cupcake.
Place the cake and cupcake pans in the center of the oven and bake at 350° until a toothpick comes out clean. About 25 minutes. Test 2 minutes prior to ensure you don't overbake.
Once baked remove pans from oven and allow to cool 10 minutes, then turn out cakes onto a cooling rack and remove cupcakes so they don't continue sitting in a warm pan. Allow the cake to completely cool. Wrap the cakes in plastic wrap and refrigerate or freeze to set the cake so it will stack nicely, if you're baking this recipe in a 13x9 pan, no need to remove or wrap in plastic, once cooled just place the pan in the fridge.
Frost cakes once they are completely cooled or chilled whichever is your preference. Check this post for frosting recipes. I prefer my cakes chilled especially when stacking them. Frost and place the cake back in the fridge to set up. Remove 30 minutes to 1 hour prior to serving.