Prepare royal icing by beating egg whites and lemon using hand mixer or electric mixer; then reduce mixing speed to low and add sifted icing sugar until combined and smooth.
Test readiness of icing by lifting mixer out of icing and allowing a dollop to drop back into bowl; if it sits on top for a few seconds before sinking into the rest of the icing, it's done.
If you need to thicken the icing, add more sifted powdered sugar. Icing needs to be used immediately as it hardens when exposed to air, so put any remaining icing in an airtight container and refrigerate.
To create the bows for the tops of your brownies, put royal icing in a piping bag with #3 tip and pipe bows on parchment paper and let dry completely.
Take a brownie square and pipe icing up all four sides of square, and then pipe a small dot on top of brownie and place bow on top. Let icing set completely before boxing up for giving.
One Last Thing
Who thought store bought brownies could look so decadent!