Preheat the oven to 375°F.
Wash and dry the bell peppers.
Cut the tops from the peppers and set them aside. Remove the seeds and white membranes.
Carefully use a small paring knife to carve jack-o’-lantern eyes and mouths into one side of each pepper.
Heat a large skillet over medium heat.
Add the ground beef and diced onion. Cook for about 6 to 8 minutes, breaking the beef into small crumbles, until browned and cooked through.
Drain excess grease if needed.
Add the garlic, Italian seasoning, smoked paprika, salt, and black pepper. Cook for about 30 seconds.
Stir in the cooked rice, drained diced tomatoes, and tomato sauce.
Cook for 2 to 3 minutes, stirring occasionally.
Remove the skillet from the heat.
Stir in 1/2 cup mozzarella and 1/4 cup cheddar.
Arrange the carved peppers upright in a baking dish.
Divide the beef and rice filling evenly among the peppers.
Sprinkle the remaining mozzarella and cheddar over the filling.
Place the pepper tops loosely over the peppers or arrange them beside the peppers in the baking dish.
Cover loosely with foil and bake for 25 minutes.
Remove the foil and bake for another 10 to 15 minutes, or until the peppers reach your preferred tenderness and the filling is hot.
Let the peppers rest for about 5 minutes before serving.
Place the little pepper lids on top and serve your jack-o’-lantern stuffed peppers warm.