1. Preheat the oven to 350ºF and prepare a 9×13 baking dish with non-stick spray.
2. Boil a large pot of water over medium heat, adding salt or chicken bouillon.
3. Add the elbow pasta to the boiling water and cook until al dente, about 7-10 minutes. Drain and set aside.
4. In a medium saucepan over medium heat, melt the butter. Stir in 1 cup of heavy cream.
5. Gradually add 1/4 cup of each shredded cheese to the butter-cream mixture, stirring until melted. If too thick, add more heavy cream, one tablespoon at a time.
6. Mix in garlic powder, mustard powder, salt, and pepper until well combined.
7. In a large bowl, combine the cooked pasta with 1/4 cup of each shredded cheese.
8. Pour the cheese sauce over the pasta and mix well.
9. Transfer half of the mixture to the baking dish, topping with more cheddar cheese. Add the remaining macaroni and cheese, then sprinkle the rest of the shredded cheese on top.
10. Cover the dish tightly with foil and place it on a flat sheet tray. Bake for 20 minutes.
11. Remove the foil and switch the oven to broil. Broil for 3-5 minutes until golden brown and bubbly, watching closely to prevent burning.
12. Let it sit for 5-10 minutes before serving. Enjoy!