In a large skillet or Dutch oven over medium-high heat, brown the ground beef and onion until the meat is fully cooked and onions are translucent.
Drain any excess fat from the pan.
Add the minced garlic, salt, pepper, ketchup, and mustard; stir for 1 minute.
Pour in the beef broth, milk, and dry macaroni. Stir to combine and ensure pasta is submerged.
Bring the liquid to a gentle boil, then reduce heat to low and cover with a lid.
Simmer for 10 to 12 minutes, stirring occasionally to prevent sticking, until the pasta is tender and most of the liquid is absorbed.
Remove from heat and stir in 1.5 cups of the shredded cheese until melted and creamy.
Top with the remaining 0.5 cups of cheese, cover for 2 minutes to allow it to melt, and garnish with pickles if desired before serving.