Cook Beef: Preheat a large skillet over medium-high heat. Add ground beef and cook until browned. Drain any excess fat.
Add Vegetables: Stir in onion, bell pepper, and garlic. Cook for 4–5 minutes, until softened.
Add Sauce & Seasoning: Pour in pizza sauce and add Italian seasoning, salt, and black pepper. Stir to combine.
Add Pepperoni: Mix in mini pepperoni slices and simmer for about 5 minutes to allow the flavors to meld.
Assemble Sloppy Joes: Spoon the mixture onto the bottom half of each hamburger bun. Sprinkle with shredded mozzarella cheese and top with the remaining bun.
