You may have seen similar recipes that are called no bake chocolate mint bars. *Technically* you don't need to bake the bottom layer with the egg, as the egg should cook in the hot butter and cocoa mixture. However, my aunt has always baked it and I prefer to do the same, just to be safe. If you chose to not bake the bottom layer, after pressing into the pan, cover and chill the bottom layer for at least one hour.