Line your pan with parchment paper, then bake your brownies according to packaged instructions. For homemade brownies, try my homemade cosmic brownie recipe! Allow to completely cool.
Spread frosting until smooth.
Use a toothpick or wooden skewer to gently "score" the brownies into 12 squares. Use the photo above to place m&m's into the cute Easter shapes.
Refrigerate brownies for 30-60 minutes until frosting is firm. Using the sides of the parchment paper, lift the brownies out of the pan.
Use a large knife to cut into 12 squares. For the cleanest cuts, dip your knife in hot water then wipe off between each cut.