In a microwave safe dish, melt the butter. You can use salted or unsalted butter for this. Add in minced garlic, Italian herbs, shredded parmesan cheese, and any salt and pepper to taste. Stir and set aside.
To assemble pepperoni pizza grilled cheese, lay out all slices of bread. Evenly slather pizza sauce onto one side of each slice. Top sandwiches evenly with shredded mozzarella, sliced pepperoni, shredded colby jack cheese. Top with other slice of bread.
When sandwiches are assembled, brush tops generously with melted compound butter.
Place the sandwiches, buttered side down, into a preheat skillet over medium low heat. Cook until deep golden brown. Just before flipping, brush the uncoated side with the remaining compound butter. Flip the grilled cheese, and cook until cheese is melted and bread is golden brown.
Remove from the pan, allow the sandwiches to sit for 3-4 minutes before slicing to serve.