Bring a large pot of salted water to a boil.
Add your pasta and cook until al dente, following the package instructions.
Drain the pasta and set it aside.
Heat olive oil in a large skillet over medium-high heat.
Add the chopped onion and sauté for 4–5 minutes, stirring occasionally, until softened.
Stir in the minced garlic and cook for an additional minute, until fragrant.
Add the ground beef to the skillet.
Cook for about 8 minutes, breaking it up with a spoon, until browned.
Drain any excess fat to prevent the sauce from becoming greasy.
Stir in the canned diced tomatoes, tomato paste, Dijon mustard, and Italian seasoning.
Let the mixture simmer for 4–5 minutes, allowing the flavors to meld and the sauce to reduce slightly.
Slowly pour in the heavy cream, stirring continuously.
Let the sauce cook for another 3–5 minutes to thicken.
Season the sauce with salt and pepper to taste.
Toss the cooked pasta with the sauce until well-coated.
Garnish with freshly grated parmesan if desired and serve hot.