Heat the oven to 375 degrees F. Slice the tops off each bell pepper and remove the seeds and ribs. Carve a simple face on the front of every pepper with a small knife.
Warm the olive oil in a skillet over medium heat. Add the onion and garlic and cook until the onion turns soft.
Add the ground turkey to the skillet and cook until it browns completely. Stir in the cooked rice, tomato sauce, salt, and black pepper. Let the mixture simmer for three minutes.
Take the skillet off the heat and stir in half of the shredded cheese until it melts into the filling.
Spoon the mixture evenly into the four carved peppers. Set them upright in a baking dish.
Sprinkle the remaining cheese over the tops. Bake for 25 minutes until the peppers feel tender when pierced with a fork.