Heat the olive oil in a large pot over medium heat. Add the ground beef and cook until browned, breaking it up with a spoon. Drain any excess fat if necessary.

Stir in the diced onion, garlic, carrot, and celery. Cook for 4-5 minutes until the vegetables are softened.

Pour in the beef broth and bring it to a boil. Add the elbow macaroni and reduce the heat to a simmer. Cook for about 8-10 minutes, stirring occasionally, until the pasta is al dente.

In a small bowl, whisk together the milk, heavy cream, and flour until smooth. Slowly pour this mixture into the pot, stirring continuously to avoid lumps. Simmer for 2-3 minutes until the soup thickens slightly.

Stir in the shredded cheddar and mozzarella cheeses, smoked paprika, mustard powder, salt, and pepper. Continue to stir until the cheese is fully melted, and the soup is creamy.

Ladle the soup into bowls and garnish with fresh parsley if desired. Serve warm with crusty bread or crackers for dipping.