In a large skillet over medium heat, cook the sausage, garlic, salt, pepper, and Italian seasoning, stirring until the sausage is browned and no longer pink. (If the garlic starts to burn, add a little vegetable oil.)
Drain any grease, then add the diced tomatoes with juice. Reserve 1 cup of marinara sauce in a bowl and set aside. Pour the remaining marinara into the skillet, stir, and let simmer for 8 minutes. Spread the reserved marinara evenly across the bottom of a 9x13 baking dish.
Slice the bell peppers in half, remove the seeds, and place them on top of the sauce in the baking dish. Turn off the heat, then spoon the meat mixture into the peppers. Top with mozzarella cheese, pepperoni, and any additional toppings you like.
Bake for 25-30 minutes, or until the peppers are soft and the cheese is melted. Serve and enjoy!
Notes
Choose bell peppers that are firm and uniform in size for even cooking. Red, yellow, or orange peppers tend to be sweeter and more flavorful, which can enhance the overall taste of the dish.
Feel free to add extra veggies like diced onions or mushrooms to the sausage mixture for added flavor and nutrition. Just sauté them along with the sausage.
If you prefer softer peppers, you can pre-bake them in the oven for 10 minutes before stuffing them with the meat mixture.