Preheat the oven to 375°F (190°C).
Prepare the bell peppers by cutting off the tops and removing the seeds and membranes. Set aside.
In a medium skillet, heat olive oil over medium heat. Add the chopped onion and minced garlic and sauté for 3-4 minutes until softened.
In a large mixing bowl, combine the sautéed onion and garlic, shredded mozzarella cheese, shredded cheddar cheese, cream cheese, cooked rice, dried oregano, dried basil, salt, black pepper, and chopped fresh parsley. Mix well until fully combined.
Stuff each bell pepper evenly with the cheese and rice mixture, pressing down gently to fill completely.
Place the stuffed peppers upright in a baking dish. Cover the dish loosely with aluminum foil.
Bake in the preheated oven for 25 minutes. Remove the foil and bake for an additional 5 minutes until the cheese is bubbly and the peppers are tender.
Remove from the oven and let cool for 5 minutes before serving.