Preheat your oven to 375°F (190°C).

Cut the tops off the bell peppers and remove the seeds and membranes. Lightly brush the outside of the peppers with olive oil and place them upright in a baking dish.

In a large skillet, heat 2 tablespoons of olive oil over medium heat. Add the diced onion and garlic, sautéing until the onion is translucent, about 3-4 minutes.

Add the ground turkey to the skillet, breaking it apart with a spoon. Cook until browned and cooked through, about 5-7 minutes.

Stir in the cooked rice, diced tomatoes, Italian seasoning, salt, and black pepper. Mix well and let it simmer for 2-3 minutes.

Remove the skillet from heat and stir in half of the mozzarella cheese.

Spoon the turkey mixture into each bell pepper, packing it down gently. Top each stuffed pepper with the remaining mozzarella cheese.

Cover the baking dish with aluminum foil and bake for 25 minutes. Remove the foil and bake for an additional 10-15 minutes, or until the cheese is bubbly and golden.

Let the stuffed peppers cool for a few minutes before serving. Garnish with fresh parsley if desired.