Preheat the oven to 375°F (190°C).

Cut the tops off the bell peppers and remove the seeds.

In a skillet, heat olive oil over medium heat and sauté the onion and garlic until softened.

Add the ground turkey and cook until browned.

Stir in cooked rice or quinoa, tomato sauce, Italian seasoning, and season with salt and pepper.

Fill each bell pepper with the turkey mixture and place in a baking dish.

If using, top with cheese.

Cover with foil and bake for 25 minutes, then remove the foil and bake for an additional 10 minutes until the peppers are tender and cheese is bubbly.