Bring a large pot of salted water to a boil. Add 8 ounces uncooked pasta and cook until al dente according to the package directions; drain and set aside while you finish the sauce.

Meanwhile, heat 1 tablespoon olive oil in a large skillet or Dutch oven over medium heat. Add 1/2 medium onion (chopped) and cook, stirring occasionally, until softened, about 4–5 minutes.

Add 1 pound lean ground beef and 3 cloves garlic (minced) to the skillet. Cook over medium heat, breaking the meat into pieces with a spoon, until the beef is browned and cooked through, about 6–8 minutes. If there is a lot of fat, spoon out and discard the excess.

Stir in 1 (14 ounce) can diced tomatoes with juices, 2 tablespoons tomato paste, 1/2 teaspoon Dijon mustard, and 1/4 teaspoon Italian seasoning. Bring to a gentle simmer and cook, stirring occasionally, for 4–5 minutes until the sauce has reduced slightly.

Pour in 3/4 cup heavy/whipping cream and stir to combine. Cook for another 3–5 minutes over medium-low heat, until the cream is heated through and the sauce has thickened a bit.

Taste the sauce and season generously with salt and pepper to your liking.

Add the drained pasta to the skillet and toss until the pasta is evenly coated with the sauce. Serve immediately, with freshly grated parmesan cheese if desired.