Bring a large pot of salted water to a boil. Cook jumbo shells 2 minutes less than package directions until just flexible but still quite firm, about 7-8 minutes. They will finish cooking in the oven. Drain, rinse with cool water, and lay flat on a baking sheet so they don't stick together.

In a large bowl, combine shredded chicken, ricotta, egg, garlic powder, salt, and pepper. Mix until well blended but don't overwork it - you want some texture from the chicken.

In a medium saucepan over medium heat, melt butter. Add minced garlic and cook 30 seconds until fragrant but not browned. Pour in heavy cream and bring to a gentle simmer. Cook 3-4 minutes until slightly thickened. Remove from heat and whisk in Parmesan and nutmeg until smooth. The sauce will thicken more as it cools.

Spread 1 cup of Alfredo sauce in the bottom of a 9x13 inch baking dish. Fill each cooked shell with about 2 tablespoons of the chicken-ricotta mixture, packing it gently. Arrange shells open-side up in the dish, nestling them close together. You should have about 18-20 filled shells.

Pour remaining Alfredo sauce evenly over the stuffed shells, making sure each one gets some love. Sprinkle shredded mozzarella over the top, then finish with a handful of extra Parmesan if you want that golden crust.

Cover tightly with foil and bake at 375F for 20 minutes. Remove foil and bake 10-15 minutes more until the cheese is bubbly and starting to brown in spots. Let rest 5 minutes before serving - this helps the filling set so your shells don't collapse on the plate.

Scatter chopped parsley over the top and serve hot. These are rich, so a simple green salad on the side cuts through the creaminess nicely.