In a large pot, heat the olive oil over medium heat. Add the diced onion and cook until translucent, about 3-4 minutes. Stir in the minced garlic and cook for an additional 1 minute until fragrant.

Add the ground beef to the pot, breaking it apart with a spoon. Cook until browned and no longer pink, about 5-7 minutes. Drain excess fat if necessary.

Stir in the diced tomatoes, tomato sauce, beef broth, Italian seasoning, salt, and black pepper. Bring the mixture to a boil.

Once boiling, add the penne pasta. Reduce heat to a simmer, cover, and cook for about 12-15 minutes, stirring occasionally, until the pasta is al dente and most of the liquid is absorbed.

Remove the pot from heat and stir in the heavy cream and shredded mozzarella cheese until melted and creamy.

Serve immediately, garnished with fresh basil if desired.