- FIRST PART 
- Place all ingredients in the first part into a saucepan over low heat. Stir until they are fully incorporated, 5-7 minutes. Remove from heat and allow to cool a bit. It should be a little thick and similar to custard. 
- SECOND PART 
- In a medium bowl, sift flour, baking soda, and baking powder together. 
- Add 1/2 cup warm butter, sugars, eggs, cooled coffee, and vanilla to the flour mixture and mix with a hand-held mixer until fully combined. (or stir by hand)  
- Add the chocolate mixture from the FIRST PART to the ingredients from the SECOND PART. Stir by hand until all ingredients are well combined. 
- Pour onto a prepared (sprayed or lined with parchment) baking sheet (I used a 10x15in baking sheet). Smooth out the batter and gently tap on the counter.  
- Bake in a 350°F oven for 16-22 minutes, or until the center no longer appears wet and an inserted toothpick is removed with a few crumbs. 
- Allow to cool before frosting.