Prep the peppers: Heat oven to 375°F (190°C).
Slice off the tops of the peppers and remove seeds and membranes. If needed, trim the bottoms slightly so they stand upright without tipping.
Soften the peppers: Brush the outsides and insides lightly with 1 tablespoon olive oil. Place in a baking dish, cut side up.
Bake for 10–12 minutes to soften slightly while you prepare the filling.
Sauté aromatics: In a large skillet, warm the remaining 1 tablespoon olive oil over medium heat. Add onion and cook 3–4 minutes until translucent. Stir in garlic and cook 30 seconds until fragrant.
Cook the turkey: Add ground turkey, breaking it up with a spoon.
Season with salt, pepper, Italian seasoning, smoked paprika, and red pepper flakes if using. Cook 5–7 minutes until no longer pink.
Add tomatoes and sauce: Stir in diced tomatoes and tomato sauce. Simmer 3–4 minutes to thicken slightly.
Taste and adjust salt and pepper.
Fold in the grain: Turn off the heat and mix in the cooked rice. The filling should be moist but not runny. If it seems dry, add a splash more tomato sauce or a drizzle of olive oil.
Stuff and top: Spoon the turkey mixture into the par-baked peppers, packing it in gently and mounding slightly.
Sprinkle cheese over the tops.
Bake: Return to the oven for 15–20 minutes, until the peppers are tender and the cheese is melted and lightly golden. If you like softer peppers, add 5 extra minutes.
Finish and serve: Let rest 5 minutes. Garnish with chopped parsley or basil.
Serve warm with a simple salad or crusty bread.