Preheat your oven to 375°F (190°C).
Cook the jumbo pasta shells according to package instructions until al dente. Drain and set aside to cool.
In a medium saucepan, heat the Alfredo sauce over medium heat. Stir in broccoli florets and cook for about 3-5 minutes until the broccoli is tender. Remove from heat.
In a large mixing bowl, combine the shredded chicken, ricotta cheese, half of the mozzarella cheese, garlic powder, onion powder, salt, and black pepper. Mix well to combine.
Stir in the cooked broccoli and Alfredo sauce mixture into the chicken and cheese filling, ensuring everything is evenly blended.
Spread a thin layer of Alfredo sauce on the bottom of the baking dish.
Stuff each jumbo shell with the chicken and broccoli filling. Place them in the baking dish, open sides up.
Once all the shells are stuffed, pour the remaining Alfredo sauce over the top, ensuring all shells are coated. Sprinkle the remaining mozzarella and Parmesan cheeses over everything.
Cover the baking dish with aluminum foil and bake in the preheated oven for 25 minutes.
Remove the foil and bake for an additional 15 minutes or until the cheese is bubbly and golden brown.
Let the dish cool for a few minutes before serving. Garnish with fresh parsley if desired.