Preheat the oven to 350°F.
Prepare brownies according to package instructions.
Remove brownies from oven and press half of the the peanut butter cups, bottoms down, into the warm brownies making rows that cover the top of the brownies entirely.
Place brownies back into the oven for one to two minutes, or until the peanut butter cups soften.
Use a spatula or knife to spread softened peanut butter cups into a gooey frosting over the brownies.
Optional: chop the rest of the peanut butter cups in half, then press them into the already-melted 'frosting' or use as garnish.
Allow to cool (if you can). Enjoy!