Preheat Oven:

Preheat the oven to 375ºF (190ºC). Lightly spray a 9×13-inch baking dish with cooking spray and set aside.
Cook Pasta:

Cook the jumbo shells according to package directions. Drain and set aside.
Prepare Filling:

In a large mixing bowl, combine shredded chicken, cottage cheese, softened cream cheese, sour cream, grated Parmesan cheese, 1 cup of shredded mozzarella cheese, and dried parsley. Mix until well combined.
Stuff the Shells:

Stuff each cooked pasta shell with the cheese mixture and place them in the prepared baking dish.
Add Alfredo Sauce:

Spread the Alfredo sauce evenly over the stuffed shells, covering them completely.
Top with Cheese:

Sprinkle the remaining shredded mozzarella cheese over the top of the Alfredo sauce.
Bake:

Bake the stuffed shells uncovered in the preheated oven for 30-35 minutes, or until the cheese is melted, and bubbly, and the shells are heated through.
Serve:

Remove from the oven and let cool slightly before serving. Garnish with additional parsley if desired. Enjoy!