In a large pot of salted boiling water, cook the tortellini according to package instructions until al dente. Drain and set aside.
In a large skillet over medium heat, add the olive oil. Once heated, add the minced garlic and sauté for about 1 minute until fragrant but not browned.
Add the diced tomatoes (with their juice) to the skillet. Stir in the Italian seasoning, salt, and pepper. Cook for 3-4 minutes until the tomatoes are heated through.
Reduce the heat to low, then slowly pour in the heavy cream while stirring. Allow the mixture to simmer for another 2-3 minutes to thicken slightly.
Stir in the cooked tortellini, chopped basil, and grated Parmesan cheese until everything is well combined. Adjust seasoning if necessary.
Plate the creamy tortellini and garnish with additional fresh basil leaves and more Parmesan cheese if desired.