In a large pot, bring 4 cups of chicken or vegetable broth to a boil. Add the elbow macaroni and cook until al dente according to package instructions. Drain and set aside.
In the same pot, reduce the heat and add the heavy cream, sharp cheddar, and mozzarella cheese. Stir until melted and smooth. Add garlic powder, onion powder, dried thyme, black pepper, and cayenne pepper if using. Fold in the cooked macaroni and crumbled sausage until well combined.
In a bowl, combine the stuffing mix with the remaining melted butter and mix well.
Preheat your oven to 350. In a greased 9x13 inch baking dish, spread the macaroni and cheese mixture evenly. Top with the stuffing mix, pressing it lightly to adhere.
Sprinkle grated Parmesan cheese over the top. Cover the dish with aluminum foil and bake for 25 minutes. Remove the foil and bake for an additional 10-15 minutes until the stuffing is golden and crispy.
Remove from the oven and let it sit for 5 minutes. Garnish with fresh parsley before serving.
Notes
Add crumbled sausage for extra flavor, optional cayenne for heat.