Preheat oven to 375°F (190°C).
Cut the tops off the bell peppers and remove the seeds. Place them upright in a baking dish.
Heat olive oil in a skillet over medium heat. Add diced onion and cook until soft.
Stir in minced garlic and cook for about 30 seconds until fragrant.
Add ground beef or chicken and cook until browned.
Stir in cooked rice, tomato sauce, diced tomatoes, Italian seasoning, paprika, salt, and pepper. Simmer for 3–4 minutes.
Spoon the filling into the prepared peppers until full.
Cover the dish with foil and bake for 25–30 minutes.
Remove the foil, sprinkle shredded cheese on top, and bake another 10 minutes until the cheese is melted.
Garnish with fresh herbs and serve warm.