Boil 6 cups of water in a large pot set over high heat, then add the pasta and cook for 7 minutes. Drain and set aside.
8 ounces dry elbow macaroni
In the meantime, heat the olive oil in a large pan set over medium heat. Add the onion and stir and cook until it becomes translucent. Stir in the garlic and stir just until it becomes fragrant, about 30 seconds.
1 tablespoon olive oil, ½ white onion, 3 cloves garlic
Add the ground beef then crumble and cook until it is no longer pink.
1 pound ground beef
Stir in the tomato paste, mustard, Worcestershire sauce, paprika, salt, and pepper, and cook for another 2 minutes.
2 tablespoons tomato paste, 1 teaspoon Dijon mustard, 1 teaspoon Worcestershire sauce, 1 teaspoon ground paprika, ½ teaspoon kosher salt, ½ teaspoon ground black pepper
Pour in the beef broth, milk, and sour cream, and whisk until fully combined.
1½ cup low-sodium beef broth, 1½ cups milk, ½ cup sour cream
Bring it to a low simmer over medium heat, then stir in the cheddar cheese until fully melted.
3 cups freshly shredded cheddar cheese
Add in the cooked pasta and stir for 3-4 minutes, or until the pasta starts to emulsify and become creamy.
Serve immediately with freshly minced parsley for garnish, if desired.