Melt butter in large skillet or Dutch oven over medium heat.
Add onion and cook 5 minutes until softened.
Add garlic and cook 30 seconds until fragrant.
Add ground beef, break up with spoon, and cook until no longer pink, then drain excess fat.
Stir in ketchup, Dijon mustard, Worcestershire sauce, seasoned salt, and black pepper.
Pour in beef broth and scrape up browned bits from bottom of pan.
Increase heat to medium-high and add elbow macaroni, stirring well.
Bring to a boil, reduce heat to low-medium, and cover.
Cook 11-13 minutes until pasta is tender, stirring occasionally.
Stir in sour cream until distributed throughout.
Remove from heat and add shredded cheddar cheese, stirring until melted and creamy.
Serve immediately.