Bring a large pot of generously salted water to a boil. Cook the pasta until just al dente, according to package directions. Before draining, reserve about 1 cup of pasta water.
Meanwhile, heat the olive oil in a large skillet or Dutch oven over medium heat.
Add the onion and cook for 3–4 minutes, stirring occasionally, until softened.
Add the garlic and cook for about 30 seconds, just until fragrant.
Add the ground beef. Season with the Italian seasoning, salt, and black pepper.
Cook for 5–7 minutes, breaking the beef into small pieces, until browned and cooked through. Drain excess fat if necessary.
Reduce the heat to medium-low. Add the pumpkin puree, tomato sauce, and broth. Stir until completely combined.
Simmer for 5–7 minutes, stirring occasionally, until the sauce has thickened slightly and the flavors have come together.
Stir in the heavy cream and Parmesan. Cook for another 1–2 minutes, stirring until the cheese has melted and the sauce is smooth.
Add the drained pasta directly to the sauce along with the fresh basil.
Toss until the pasta is thoroughly coated. Add reserved pasta water a little at a time as needed until the sauce becomes glossy and coats the pasta beautifully.
Taste and adjust the salt and black pepper.
Serve immediately with additional Parmesan, basil, black pepper, or red pepper flakes.
