Preheat the oven to 375°F. Slice the tops off each bell pepper and remove the seeds and membranes. Use a small knife to carve simple jack-o'-lantern faces into the sides of the peppers.
Heat the olive oil in a large skillet over medium heat. Add the diced onion and cook for 3 minutes until it softens. Stir in the minced garlic and cook for 1 minute more.
Add the ground turkey to the skillet. Cook, breaking it up with a spoon, until it is no longer pink. Stir in the cooked rice, drained diced tomatoes, paprika, salt, and black pepper. Cook for 2 minutes to combine.
Remove the skillet from the heat and mix in half of the shredded cheddar cheese. Spoon the filling evenly into the carved bell peppers.
Place the stuffed peppers in a baking dish. Sprinkle the remaining cheese over the tops. Bake for 25 minutes until the peppers are tender and the cheese is melted.