Preheat your oven to 375°F (190°C). Grease a baking dish with nonstick spray.

Cut the tops off the bell peppers and remove the seeds. Trim their bottoms if needed to stand upright.

In a skillet over medium heat, sauté the diced onion until translucent. Add garlic and cook until fragrant.

Add ground turkey to the skillet and cook until browned. Stir in cooked rice, diced tomatoes, salt, pepper, and any optional spices until well combined.

Stuff each pepper generously with the turkey mixture and place them upright in the baking dish.

Cover with foil and bake for about 30 minutes. Remove foil, sprinkle cheese on top, and bake uncovered for an additional 10 minutes until bubbly.