I make a chocolate topping for my brownies my melting chocolate chips and then spreading it over the brownies. I then stick the brownies in the freezer so it hardens. Once the brownies come to room temperature the topping is not as hard as I would like and is very susceptible to melting. Is there anything I can do to make it harder and more heat resistance. I want something more like a candy bar topping and not icing. When answering keep in mind I'm not a professional pastry chef or chocoaltier. I run a small business but have no professional knowledge.