Note: As you may know, anytime you work with chocolate chips they can harden and clump up. This can happen especially if there is any water present. Make sure your bowl and stirring utensil is dry. If the mixture hardens and clumps up, add 1 to 2 Tablespoons of oil to the recipe and heat a minute longer. When I have to add oil, I use Coconut Oil. It tastes great and is healthy for you, but any cooking oil will work.