Begin by boiling a large pot of salted water over high heat. Add a generous amount of medium pasta shells and cook according to the package instructions until al dente, usually around 8–10 minutes. Once done, drain the pasta in a colander and set it aside to cool slightly.

In a large skillet, heat 2 tablespoons of olive oil over medium-high heat. Add the ground beef to the hot skillet, breaking it up with a spatula. Cook for about 3–5 minutes, or until the beef is browned and no longer pink. Drain any excess fat.

Add one diced sweet onion to the skillet and sauté for approximately 2 minutes, then add 2 minced garlic cloves and cook for another 30 seconds until fragrant.

Sprinkle 2 tablespoons of all-purpose flour over the beef and onion mixture. Whisk continuously for about 1–2 minutes.

Gradually whisk in 2 cups of beef stock, then add 1 cup of marinara sauce, Italian seasoning, dried parsley, dried oregano, and smoked paprika. Simmer for 6-8 minutes.

Fold in the cooked pasta along with the beef mixture. Add 1 cup of heavy cream and stir gently until combined. Adjust seasoning with salt and pepper to taste.

Remove the skillet from heat and stir in a dollop of sour cream and 1 cup of shredded cheddar cheese. Mix until the cheese is melted and the sauce is creamy and smooth.