Preheat oven to 400°F (200°C). Line a large baking dish with foil or lightly grease it.

Halve the bell peppers lengthwise and remove the seeds and membranes. Drizzle the cut sides lightly with olive oil and season with salt and pepper.

Place the peppers cut-side down in the baking dish and roast for 10 minutes. This head start ensures tender, slightly caramelized pepper walls. Remove from oven and flip cut-side up. Set aside.

Heat 1 tablespoon of olive oil in a large skillet over medium-high heat. Add the diced onion and cook, stirring occasionally, for 3-4 minutes until softened and translucent.

Add the minced garlic and cook for 30 seconds until fragrant.

Add the ground beef to the skillet. Let it sit undisturbed for 1-2 minutes to develop a crust, then break it apart and cook until fully browned, about 6-8 minutes total. Drain excess fat if needed.

Stir in the tomato paste and cook for 1 minute to caramelize slightly. Add the crushed tomatoes, Worcestershire sauce, Italian seasoning, garlic powder, smoked paprika, salt, and black pepper. Stir well to combine.

Reduce heat to medium and simmer for 5 minutes until the sauce thickens slightly. Remove from heat and fold in the cooked rice until fully incorporated. Taste and adjust seasoning.

Spoon the beef and rice filling generously into each par-roasted bell pepper half, mounding it slightly above the rim.

Mix the shredded mozzarella and grated parmesan together in a small bowl. Top each stuffed pepper with a generous handful of the cheese mixture.

Cover the baking dish loosely with foil and bake at 400°F for 20 minutes.

Remove the foil and switch the oven to broil on high. Broil for 2-3 minutes until the cheese is bubbling, golden, and lightly browned in spots. Watch closely to prevent burning.

Remove from the oven and let the peppers rest for 5 minutes. Garnish with fresh chopped parsley and serve immediately.