With all the boxed brownie mixes available, why not jazz them up a bit?br According to Business Insider, one out-of-the-box idea is to add an extra egg.br Doing so will make the batter thick enough to withstand the heat of a waffle iron!br Or, mix up the brownies first, then add a layer of chocolate-chip cookie dough on top. Decadence!br Finally, try adding brownie batter to Rice Krispie treat batter.