Preheat the oven to 350 degrees and then either grease the 9x13 inch cake pan or lay down parchment paper.
In a large bowl, whisk together the dry ingredients until they're well combined.
In a separate bowl, add in all the wet ingredients except for the boiling water and coffee. Blend well using the scraper (I prefer this at this point) or the whisk. Use a scraper as needed to scrape the side and make sure everything is combined properly.
Add the wet ingredients to the dry ingredients and slowly combine them.
Then a little at a time, add in the boiling water and hot coffee. Whisk in between adding little by little.
Pour the batter into the prepped baking pan and bake on the middle rack for 25 to 30 minutes. Check after 25 minutes with a tooth pick and if it comes out dry, then remove the cake. If not, add it back in for a few minutes.
While the cake cools, combine the butter and powdered sugar for the frosting ingredients and mix with a hand mixer. Then add in the rest of the ingredients. You can let the frosting sit out until the cake has cooled long enough to be frosted.