My coworker requested peanut butter treats for her birthday last week. She's got good taste! These brownie cups were a great way to fulfill that request, and, as a bonus, they were simple enough to make on a weeknight. The brownies are the same as the ones that I made for my S'mores Brownie Cups. The filling is just melted peanut butter - literally just that. So easy! I love these brownie cups...you can fill them with so many different flavors. But the original peanut butter is still my go-to!