In a small microwave safe bowl, melt butter. Stir in garlic herb seasoning. Brush on buns, and toast on grill or in skillet for ~1 minute per side.
In a large bowl, combine ground beef, sausage, and Italian seasoning. Form in 4 even patties. Add salt and pepper and indent the center of each with your thumb.
Cook on preheated grill pan ,or outdoor grill for ~4-5 minutes per side. Cook to 160 degrees F for a well done burger.
Top with sauce, mozzarella, pepperoni, and finally Parmesan cheese. Place onto prepared bun.