Begin by boiling a large pot of salted water over high heat. Add the medium pasta shells and cook according to package instructions until al dente, typically around 8-10 minutes. Once cooked, drain the pasta well and set it aside while you prepare the creamy sauce.

In a large skillet, heat 1 tablespoon of olive oil over medium-high heat. Add 1 pound of ground beef to the skillet, breaking it apart with a spatula. Cook for 3-5 minutes, or until the beef is well browned and no longer pink. Drain excess fat, leaving just enough to keep the flavor, then set the beef aside.

In the same skillet, add a bit more olive oil if necessary and toss in a diced sweet onion. Sauté for about 2 minutes, or until the onion becomes translucent and fragrant. Stir occasionally to ensure even cooking and to prevent sticking.

Add 2 minced garlic cloves to the skillet, cooking for an additional 1 minute. Continue to stir as the garlic sauté, infusing the dish with a delicious fragrance.

Sprinkle in 2 tablespoons of all-purpose flour, stirring constantly as it cooks for about 1 minute.

Gradually pour in 2 cups of beef stock and 1 cup of marinara sauce, whisking constantly. Allow this mixture to come to a gentle simmer for 6-8 minutes.

Add the cooked ground beef back into the skillet, stirring until it’s well coated with the sauce. Then, incorporate the drained pasta shells.

Reduce the heat to low and pour in 1 cup of heavy cream, stirring to blend thoroughly. Cook for another 1-2 minutes, until everything is heated through and bubbling gently.

Mix in ½ cup of sour cream and 1 cup of shredded cheddar cheese, folding carefully until the cheese melts and the sauce becomes extra creamy.

Spoon the creamy beef and shells into bowls and serve hot, garnished with a sprinkle of dried parsley if desired.