For a milder brownie, use 1/3 C cocoa powder and 2 tsp instant coffee. Keep in mind that I used a medium roast coffee so if you're using a darker coffee consider starting with less.
I also crushed the instant coffee slightly with the back of a spoon to get rid of the large granules, but I'm not sure that was necessary so you can do that if you want.
These brownies do get a little drier once they sit overnight and if they're kept in the fridge so consider adding 1 tbsp water when adding the cocoa and coffee granules.
Try putting 1 brownie in the microwave for 5-10 seconds(depending on whether it was in the fridge or not) for an even more delicious treat!