Line your brownie pan with parchment paper to make removing them easy. Mix brownies according to the instructions on the box and fill the pan. Bake for a few minutes until you notice it about to go from liquid to solid.

Add a few Reeses Peanut Butter cups on top and push into the mix until they are embedded. You can skip this step if nut allergies are an issue.

Continue baking according to package directions, but take out of the oven 5 minutes early. The brownies will be almost cooked but still a teeny bit soft. Remove from the oven and carefully push the candy pieces into the top of the brownies.

Place back in the oven and bake for 5 more minutes, keeping a careful eye so the candy doesn’t totally melt. A little melting is okay, it adds to the gooey ‘Monster Mash’ look.

Remove from oven and let cool. That’s the hardest part, WAITING!