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.
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 PARStir 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.