Heat a large skillet over medium-high heat. Add the ground beef along with the chopped onion and minced garlic. Cook until the beef is fully browned, and the onion is tender. Drain any excess grease if necessary.

Stir in the dry parsley, Italian seasoning, red pepper flakes, salt, and ground pepper. Mix everything well to combine the flavors.

Add the tomato paste and Worcestershire sauce to the skillet. Stir until everything is evenly blended and coated with sauce.

Pour in the low-sodium beef broth and add the elbow macaroni. Stir everything together, then bring to a simmer. Cover the skillet and cook for 10 minutes, stirring every 2-3 minutes to prevent sticking.

After 10 minutes, uncover the skillet and stir in the milk and sour cream. Then, add 1 cup of shredded cheese, stirring until the mixture is thick and creamy. If it looks too watery, simmer uncovered for an additional 1-2 minutes.

Sprinkle the remaining shredded cheese on top of the casserole. Cover the skillet again and heat for 2-3 minutes, or until the cheese is fully melted.

Scoop the cheesy casserole into bowls and serve warm. If desired, garnish with chopped parsley or green onion for an extra pop of flavor.