Bring a large pot of salted water to a boil. Add the 8 oz of large pasta shells and cook according to package instructions until al dente. Once cooked, drain the shells in a colander and set aside. Try not to overcook the pasta since it will continue to cook slightly when mixed with the hot sauce later.
Heat 2 tablespoons of olive oil in a large skillet over medium heat. Add the chopped onion and cook for about 3-4 minutes until softened and translucent. Stir in the minced garlic and cook for another 30 seconds, just until fragrant.
Add the ground beef to the skillet with the onions and garlic. Break it up with a spatula and cook until the beef is browned and cooked through, about 6-8 minutes. Season with salt, pepper, and 1 teaspoon of Italian seasoning during the cooking process. Once cooked, drain any excess fat if needed.
Pour in 1 cup of beef broth and bring to a gentle simmer. Let it reduce slightly for 3-4 minutes. Then, stir in 1 cup of heavy cream and continue to simmer for another 3-5 minutes, allowing the sauce to thicken slightly.
Lower the heat and stir in 1 cup of shredded cheddar cheese until melted and smooth. Taste and adjust seasoning with additional salt and pepper if necessary.
Add the cooked pasta shells back into the skillet with the creamy beef sauce. Gently toss to coat each shell in the flavorful sauce. Cook together for 1-2 minutes to ensure everything is warmed through.
Remove from heat and sprinkle fresh parsley over the top for a bright, fresh finish. Serve immediately and enjoy the cozy, cheesy goodness!