Prepare the Pasta: Cook pasta in salted boiling water according to package directions until al dente. Drain, reserving 1/2 cup of pasta water, and set aside.
Cook the Ground Beef: Heat a large skillet over medium heat. Add ground beef and cook, breaking it up with a spoon, until browned and fully cooked (about 6-8 minutes). Drain excess fat and transfer the cooked beef to a plate.
Sauté the Aromatics: In the same skillet, add olive oil and sauté the diced onion and minced garlic until fragrant (about 2 minutes).
Build the Creamy Sauce: Reduce heat to medium-low and stir in the heavy cream. Bring to a gentle simmer. Add shredded cheddar cheese and stir until fully melted and smooth. Season with Italian seasoning, salt, and black pepper.
Combine Everything: Return the cooked ground beef to the skillet. Add the cooked pasta and toss to coat in the sauce. Use reserved pasta water to adjust the sauce to your desired consistency. Stir in optional vegetables like bell peppers, spinach, or mushrooms, and cook until tender but still vibrant.
Serve: Plate the pasta hot and garnish with additional cheese or fresh herbs if desired.