1️⃣ Cook the pasta: Bring a large pot of salted water to a boil. Cook the pasta shells according to package instructions until al dente. Drain and set aside.

2️⃣ Brown the beef: Heat olive oil in a large skillet over medium-high heat. Add the ground beef and cook until browned, about 3-5 minutes, breaking it up into small pieces with a spoon. Drain any excess fat and transfer the beef to a plate.

3️⃣ Sauté onion and garlic: In the same skillet, add the diced onion and sauté for 2 minutes until softened. Stir in the minced garlic and cook for another 1 minute until fragrant.

4️⃣ Make the roux: Sprinkle the flour over the onion and garlic mixture. Cook, whisking constantly, for 1 minute until the flour is lightly browned.

5️⃣ Add liquids and seasonings: Gradually whisk in the beef stock, ensuring no lumps form. Stir in the marinara sauce, Italian seasoning, parsley, oregano, and smoked paprika.

6️⃣ Simmer the sauce: Bring the sauce to a boil, then lower the heat to a gentle simmer. Cook for 6-8 minutes, stirring occasionally, until the sauce has thickened slightly.

7️⃣ Combine pasta and beef: Return the cooked pasta and browned beef to the skillet. Stir to coat everything evenly in the sauce.

8️⃣ Incorporate dairy: Mix in the heavy cream and simmer for 1-2 minutes until heated through. Adjust the seasoning with salt and pepper as needed. Then, stir in the sour cream for added creaminess.

9️⃣ Add the cheese: Fold in the grated cheddar cheese and stir until melted and fully incorporated into the sauce.

🔟 Serve: Serve the creamy beef and shells immediately, garnished with chopped parsley if desired. Enjoy this rich, flavorful dish!