Preheat your oven to 425 degrees F.
Cook the rice according to the package instructions. While it cooks, cut the tops off the peppers and remove the stems, membranes, and seeds. Slice a little off the bottoms so they stand up and don’t tip over, and set the tops aside so you can dice them.
Place the bell peppers upright in a greased oven-safe baking dish and season lightly with salt and pepper, then bake uncovered for 20 minutes.
Add a little oil to a pot, then add the onions and the diced peppers from the tops. Cook over medium-low heat for about 3–4 minutes.
Stir in the garlic and tomato paste and cook for 1 minute. Add more oil if it starts drying up.
Add the ground beef and break it up as it cooks. Cook until fully browned.
Stir in the garlic powder, onion powder, Italian seasoning, paprika, 1 teaspoon kosher salt, and black pepper. Cook for about 1 minute, then add the tomato sauce and water. Let it simmer for 2–3 minutes, then stir in the cooked rice, 1/2 cup mozzarella cheese, Worcestershire sauce, and hot sauce. Mix well and taste for seasoning, adding more salt and pepper if needed.
Fill each pepper with the beef and rice mixture all the way to the top, then sprinkle mozzarella cheese over them. Bake for 12–15 minutes and enjoy.