6ouncesshredded extra-sharp cheddar cheeseabout 1 ½ cups
In a large pot of boiling salted water, cook pasta according to package instructions. Drain well
Heat olive oil in a large skillet over medium-high heat. Add ground beef and cook until brown, about 3-5 minutes, crumbling the ground beef. Drain excess fat and set aside
Add onion to the skillet, cook stirring frequently until translucent, about 2-3 minutes.
Stir in garlic, Italian seasoning, paprika and mustard powder, cook about 1 minute
Whisk in flour until lightly browned, about 1 minute
Gradually whisk in beef stock and tomato sauce. Bring to a boil, reduce heat and simmer, stirring occasionally until reduced and slightly thickened, about 6-8 minutes.
Stir in pasta, beef and heavy cream and heat through. Season with salt and pepper.
Stir in cheese until melted.
To Store: Store any leftover creamy beef and shells, let it cool completely before transferring it to an airtight container and placing it in the fridge.You can keep it refrigerated for up to 3 days. Keep in mind that once chilled, the pasta will absorb more sauce. When reheating, you may need to add a bit more heavy cream or beef stock.