Preheat your oven to 375°F (190°C).
Cook the large pasta shells according to package instructions until al dente, typically about 8-10 minutes. Drain and set aside.
In a large bowl, combine the shredded chicken, ricotta cheese, 1/2 cup of mozzarella, Parmesan, Cajun seasoning, diced bell pepper, and green onions. Mix well and season with salt and pepper to taste.
Stuff each pasta shell generously with the chicken mixture, placing the filled shells in a greased baking dish.
In a saucepan over medium heat, combine the heavy cream and remaining mozzarella. Stir until the cheese is melted and the mixture is smooth and creamy.
Pour the creamy sauce over the stuffed shells, making sure to cover them well. This prevents the pasta from drying out during baking.
Bake in the preheated oven for about 25-30 minutes, or until bubbly and golden on top.
Allow the stuffed shells to cool for a few minutes before serving. Garnish with additional green onions or parsley if desired.