Boil a large pot of salted water. Cook the pasta shells according to package instructions until al dente. Drain and set aside to cool slightly.
In a skillet, heat olive oil over medium heat. Add the diced green bell pepper and onion; sauté until softened, about 5 minutes. Remove from heat.
In a large bowl, combine the cooked chicken, ricotta cheese, half of the mozzarella cheese, grated Parmesan cheese, Cajun seasoning, garlic powder, onion powder, and the sautéed bell pepper and onion. Mix well and season with salt and pepper to taste.
Carefully fill each pasta shell with the chicken mixture, placing them seam-side up in a greased 9x13 inch baking dish.
Pour marinara sauce evenly over the stuffed shells. Sprinkle the remaining mozzarella cheese on top.
Cover the dish with foil and bake for 20 minutes. Remove the foil and bake for an additional 10 minutes, or until cheese is bubbly and golden.
Allow to cool for a few minutes before serving. Garnish with chopped fresh parsley on top for a pop of color.
Notes
Garnish with fresh parsley for added flavor and color.