1. Cook shells in salted boiling water until al dente, drain, and toss with oil to prevent sticking

2. Sauté chicken in a skillet over medium heat until cooked through and lightly golden, season with salt and pepper

3. Steam broccoli until tender, chop finely, and set aside

4. In a bowl, beat cream cheese with one cup of Alfredo sauce until smooth, then stir in half the mozzarella, Parmesan, garlic, and Italian seasoning

5. Fold cooked chicken and broccoli into the cheese mixture until well combined

6. Butter a 9×13 inch baking dish and spread 1/2 cup Alfredo sauce on the bottom

7. Fill each shell with the chicken mixture and arrange them snugly in the dish

8. Pour remaining Alfredo sauce over the shells and sprinkle with the reserved mozzarella cheese

9. Cover the dish with foil and bake at 375 F (190 C) for 20 minutes, then uncover and bake an additional 10 minutes until the cheese is bubbly and golden

10. Let rest for 5 minutes, garnish with parsley, and serve