Preheat your oven to 350°F (175°C) and grease a 9x13 inch baking pan.
In a large bowl, mix the melted butter, granulated sugar, and brown sugar until well combined.
Add the eggs one at a time, mixing well after each addition, then stir in the vanilla extract.
In another bowl, whisk together the flour, cocoa powder, baking powder, and salt.
Gradually add the dry ingredients to the wet ingredients, mixing until just combined.
Fold in the mini marshmallows and chocolate chips.
Pour half of the brownie batter into the prepared baking pan and spread evenly.
Sprinkle the graham cracker crumbs over the batter, then add the remaining brownie batter on top.
Use a spatula to smooth it out and sprinkle the red and blue M&M's on top.
Bake in the preheated oven for 25-30 minutes, or until a toothpick inserted into the center comes out with a few moist crumbs.
Allow the brownies to cool in the pan for at least 15 minutes before cutting into squares.