Make the brownie batter and then divide it into two batches. Place each batter in a 9 inch cake pan and bake the two for slightly less time (5 minutes less) than the full batch calls for.
Cool the brownie layers of the cake.
Place one of the brownie cakes on top of clean cardboard, and then fit this bottom brownie layer onto the bottom of a spring-form pan. Place the ring of the pan on the brownie layer.
Slip wax paper or parchment paper in between the ring and the brownie layer, so it is around the total circumference of the brownie layer.
Add 2 cups of ice cream on top of the brownie layer.
Place another brownie layer on top of the ice cream layer.
Place another 2 cups of ice cream on top of the second brownie layer.
Decorate the top as desired and place in the freezer for a few hours.
Serve with candles and a howling rendition of the happy birthday song.