Bring a large pot of salted water to a boil and cook the pasta shells until al dente, about 8-10 minutes. Reserve 1/2 cup of pasta water, then drain and set aside.

In a heavy-bottomed cast iron skillet over medium heat, cook the ground beef until browned and crumbly, about 5-7 minutes. Drain excess grease if necessary.

If the pan looks dry, add olive oil. Stir in the diced onion and cook for 3-4 minutes until softened and translucent.

Add garlic, tomato paste, Italian seasoning, red pepper flakes, salt, and black pepper. Stir for about 1 minute until the mixture is fragrant.

Pour in the chicken broth, scraping up any flavorful bits from the skillet to incorporate into the sauce.

Lower the heat and stir in the heavy cream and parmesan cheese until the sauce is smooth and creamy.

Add the halved cherry tomatoes and cook for about 2 minutes until they gradually soften.

Toss in the drained pasta shells, ensuring they are fully coated with the sauce. Use reserved pasta water as needed to loosen.

Top with chopped basil and add extra parmesan before serving warm.