Preheat your oven to 375°F (190°C).
Slice the tops off the bell peppers and carefully remove the seeds and internal membranes.
In a large skillet over medium heat, add the olive oil and ground beef.
Cook the beef until fully browned, using a spatula to break it into small crumbles.
Stir in the garlic powder, onion powder, sea salt, and black pepper to season the meat.
Add the cooked brown rice and tomato puree to the skillet, stirring until the mixture is well combined and heated through.
Spoon the beef and rice mixture into the hollowed-out bell peppers, pressing down slightly to pack the filling.
Place the stuffed peppers upright in a baking dish and sprinkle the tops with parmesan cheese.
Bake for 25 to 30 minutes until the peppers are tender and the cheese on top is golden and bubbly.