Sauté: In a large skillet, melt the butter over medium-high heat. Add the steak cubes and cook until browned on all sides. Add the shrimp and minced garlic, sautéing for another 2–3 minutes until the shrimp are pink and opaque. Remove the protein from the pan and set aside.
Pasta: While the meat cooks, boil your macaroni in salted water according to the package instructions. Drain and set aside.
The Sauce: In a clean saucepan (or the same skillet to catch the pan drippings), pour in the heavy cream. Bring to a gentle simmer over medium heat. Whisk in the shredded cheddar cheese until completely melted and the sauce is smooth and thick.
Combine: Fold the cooked macaroni, steak, and shrimp back into the cheese sauce. Stir gently to ensure every piece of pasta and protein is thoroughly coated.
Serve: Serve immediately while the sauce is hot and silky.