Preheat your oven to 350 degrees

Grease (or, line with parchment paper) a brownie pan

In a bowl, mix all your dry ingredients together, and then add your eggs and butter, mix until no lumps are left

Pour your brownie mix into your pan and add in your marshmallows, make sure to push them in so the batter covers the top of the marshmallows

Bake at 350 for 20-30 mins

Let cool before cutting and enjoy!