Preheat your oven to 375°F (190°C). Slice the bell peppers in half lengthwise and remove seeds and membranes. Place them in a baking dish cut side up.
In a large bowl, mix together the shredded chicken, cream cheese, sour cream, cheddar, mozzarella, garlic, onion powder, smoked paprika, salt, and pepper. Stir until well combined and creamy.
Spoon the creamy chicken mixture evenly into each pepper half, pressing down slightly to fill them fully.
Top each stuffed pepper with a bit of extra shredded cheese. Cover the dish loosely with foil and bake for 25 minutes. Remove the foil and bake uncovered for another 5–10 minutes, or until the cheese is bubbly and slightly golden.
Let the peppers cool for a few minutes. Garnish with chopped parsley or green onions if desired, and serve warm.