In a large pot of salted boiling water, cook the pasta shells according to package instructions until al dente. Drain and set aside.

In a large skillet, heat olive oil over medium-high heat. Add the ground beef and cook, breaking it apart with a spoon, until browned. Drain any excess fat.

Add diced onion to the skillet and sauté until softened, about 3-4 minutes. Stir in garlic, Italian seasoning, paprika, salt, and pepper. Cook for 1 minute until fragrant.

Sprinkle flour over the beef mixture and stir until fully combined. Gradually add beef broth, stirring constantly, until the mixture thickens. Reduce heat to low and stir in heavy cream. Simmer until the sauce is smooth and creamy.

Remove the skillet from heat and stir in cheddar cheese and Parmesan cheese until melted and smooth.

Add the cooked pasta shells to the skillet and toss to coat evenly with the cheesy beef sauce. Garnish with chopped fresh parsley, if desired.

Scoop the creamy cheesy beef and pasta shells onto plates and serve hot.