Season the chicken with granulated garlic, onion powder and chicken bouillon. Cook chicken by desired method; this can be 4-hours on high in a slow cooker, pan-fried, or baked. Once fully cooked, shred with two forks and set aside.

Melt butter over medium heat in a large skillet. Add the onions, Italian seasoning, salt, and pepper. Stir occasionally, cooking for about 25 - 30 minutes, or until the onions have caramelized. Turn off the heat, stir in the minced garlic, and set aside.

While the onions are cooking, cook the pasta shells in boiling water according to the packaged directions. Drain, and set aside to cool.

Mix together the ricotta, egg, Swiss cheese, grated parmesan, half of the caramelized onions, and chicken together in a large bowl. This will be your filling.

Stuff each shell with the filling, trying not to overstuff. Place in a casserole dish and continue until each shell has been stuffed.

Preheat the oven to 400F.

Add 1 tablespoon of butter to a large skillet over medium-high heat. Once melted, add the flour and continuously whisk together for 1 minute. While whisking, slowly add the chicken stock and then the dry sherry vinegar. Bring to a boil, turn off the heat, and whisk in the heavy cream. Fold in the remaining onions to create a sauce.

Pour sauce over the stuffed pasta shells. Sprinkle with Italian breadcrumbs and mozzarella. Bake uncovered for 25 minutes, or until a golden crust has formed on the top. Serve immediately with Italian parsley.