Preheat the oven to 350℉ and line a baking sheet with parchment paper. Set aside.
Slice French bread in half lengthwise and place on the prepared baking sheet. In a small bowl, add softened butter, garlic salt, and Italian seasoning. Mix until well combined. Evenly spread the garlic butter mixture over the two halves of bread.
In a large skillet over medium-high heat, add the ground beef to the skillet. Cook for 6-8 minutes or until browned, breaking up the ground beef with a spatula.
Add onions, green peppers, and garlic, and cook for 4-5 minutes or until they become soft. Then, drain off excess grease.
Add tomato sauce, ketchup, brown sugar, mustard, Worcestershire sauce, pepper, salt, onion powder, and paprika. Stir until combined and simmer uncovered for 6-8 minutes or until the sauce thickens.
Divided the sloppy joe mixture in half and top each loaf of garlic bread. Then, sprinkle the cheese over the top of each loaf. Bake for 12-14 minutes or until cheese is melted and golden brown.
Cut into pieces before serving and enjoy!