While the pasta is cooking, in a large skillet on high heat add the ground beef and sauté for 5 minutes, mixing occasionally. Next, add in the garlic and onions and sauté for 5 minutes, mixing occasionally.
Lower to medium heat and add in the marinara sauce and cook for 5 minutes, mixing occasionally.
Next, add in the cooked elbow pasta and cheddar cheese.
Continuing on medium heat cook for 2 minutes, mixing occasionally, or until the cheese is melted and combined.