Step 1: Cook the Pasta

Start by bringing a large pot of salted water to a boil. Add the pasta shells and cook them until al dente, according to package instructions. This typically takes about 8–10 minutes. Drain the pasta, reserving about 1/2 cup of the cooking water in case you need to adjust the sauce’s consistency later. Set the pasta aside.

Step 2: Brown the Beef

Heat the olive oil in a large skillet or Dutch oven over medium-high heat. Add the ground beef, breaking it apart with a spoon or spatula, and cook until browned and fully cooked, about 5–7 minutes. Season lightly with salt and pepper as it cooks. Once done, drain off any excess grease and transfer the beef to a plate.

Step 3: Sauté the Aromatics

Using the same skillet, add the diced onion and cook for about 3–4 minutes, stirring frequently, until softened and slightly translucent. Add the minced garlic and cook for an additional minute, just until fragrant.

Step 4: Make the Roux

Sprinkle the flour over the onions and garlic, stirring constantly to coat them evenly. Cook the mixture for 1–2 minutes, letting the flour toast lightly. This step is crucial for thickening the sauce and creating a smooth, velvety texture.

Step 5: Build the Sauce

Slowly pour in the beef stock, whisking continuously to prevent lumps. Once the stock is fully incorporated, stir in the marinara sauce, Italian seasoning, parsley, oregano, smoked paprika, and a pinch of salt and pepper. Bring the sauce to a simmer and let it cook for 6–8 minutes, allowing the flavors to meld and the sauce to thicken slightly.

Step 6: Add the Dairy

Reduce the heat to low and stir in the heavy cream. Let the mixture heat through for 1–2 minutes, then add the sour cream, whisking gently until the sauce is smooth and creamy. Taste the sauce and adjust the seasoning as needed.

Step 7: Combine Pasta and Beef

Return the cooked pasta shells and browned beef to the skillet, tossing to coat everything evenly in the creamy sauce. If the sauce feels too thick, stir in a splash of the reserved pasta water to loosen it.

Step 8: Add the Cheese

Fold in the grated cheddar cheese, stirring until it melts completely into the sauce. This step adds richness and ties all the flavors together, making the dish wonderfully cheesy and satisfying.

Step 9: Serve and Enjoy

Serve your Creamy Beef and Shells immediately, garnished with a sprinkle of parsley or an extra pinch of cheese for a little extra flair. Pair it with a side salad, garlic bread, or steamed vegetables for a complete meal.