Cook the Pasta: Bring a large pot of salted water to a boil. Add medium pasta shells and cook until just under al dente, about 2 minutes less than package instructions. Drain and rinse under cold water. Set aside.

Brown the Beef: Heat olive oil in a large skillet over medium-high heat. Add ground beef and cook for 3-5 minutes until browned. Drain excess fat.

Add Onions and Garlic: Stir in diced sweet onion, cooking for about 2 minutes until translucent. Add minced garlic and sauté for 1 more minute.

Whisk in Flour: Sprinkle all-purpose flour over beef and onion mixture. Stir and cook for 1 minute. Gradually whisk in beef stock, ensuring no lumps.

Combine Sauces and Spices: Add marinara sauce, Italian seasoning, dried parsley, dried oregano, and smoked paprika. Bring to a boil, then simmer for 6-8 minutes until thickened.

Stir in Pasta and Cream: Add drained pasta and browned beef back to the skillet. Stir in heavy cream and cook for 2-3 minutes.

Mix in Sour Cream and Cheese: Fold in sour cream until smooth. Gradually add cheddar cheese, mixing until melted.

Serve and Garnish: Serve immediately, garnished with extra cheese or herbs if desired. Enjoy!