With an electric mixer, beat together cream cheese, diced pepperoni, spaghetti sauce, 3 cups of mozzarella, and parmesan.
Spread mixture into an 8x8" casserole dish or large pie plate. Top with remaining 1 cup of mozzarella, then remaining whole pepperoni slices. If desired, sprinkle with garlic salt.
Bake at 425F for about 20 minutes until cheese is hot, bubbly, and melted through, and pepperoni is crisping around the edges.
Serve with crackers, bread sticks, or garlic toast.
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Notes
Calories are automatically generated. For best results calculate based on your exact ingredients.Slow cooker variation:
Beat together cream cheese, diced pepperoni, spaghetti sauce, mozzarella, and parmesan. Spread mixture into the crockpot.
Top with remaining mozzarella, then whole pepperoni slices. Sprinkle with garlic salt. Cover and turn on heat until cheese is melty (at least one hour on low).