Stick brownies in the freezer and allow them to cool.
Cut brownies into triangles.
Embellish hats with frosting.
Enjoy!
Notes
It doesn't matter whether brownies are in the freezer for an hour or overnight, they will not be frozen solid, and you should be able to cut them right after pulling them out.I used a flower tip to pipe the frosting onto the Santa Hats. I love how they turned out!