Preheat a large heavy-bottomed skillet with a lid (or Dutch oven) over medium heat.
Add 1 tablespoon of butter to the skillet and allow it to melt.
Add in the onions, and cook until softened - about 5 minutes.
Then add the garlic to the skillet and cook just until fragrant - about 30 seconds.
Quickly add the ground beef to the skillet, using the bottom of a wooden spoon to crumble it.
Cook the ground beef until no longer pink, then drain any excess fat.
Add in the ketchup, dijon mustard, Worcestershire sauce, seasoned salt, and black pepper, and stir until combined.
Pour in the beef broth and use the bottom of a wooden spoon to scrape up any browned bits on the bottom of the skillet.
Increase the heat to medium-high and add in the elbow macaroni. Stir well.
Once the liquid begins to boil, reduce the heat to low-medium and place the lid on top of the skillet.
Cook for 11-13 minutes, or until the pasta is cooked to your liking.
Stir the pasta to loosen any stuck-on pieces on the bottom, then add in the sour cream (or heavy cream) and stir until well distributed.
Remove the skillet from the heat and add in the shredded cheddar cheese, stirring until it’s completely melted.
Serve immediately.