Make brownie batter according to directions. Bake them into cupcakes. Cool.
Frost the cupcakes with cool-whip or white frosting.
Frost the sugar cones with red frosting.
Lightly frost the cones (just enough to allow for the glitter to stick)
Roll the frosted cone in edible red glitter.
Put cool-whip or white frosting in the center of the cones (for added fun)-optional
Set the cone on top of the frosted cupcake with the pointy end up.
Push a mini marshmallow onto the pointed end of the cone.
Pipe whipped cream or frosting around the cone to look like the bottom of Santa's hat.