Heat olive oil in a large skillet over medium heat.
Add minced garlic and sauté for 1-2 minutes until fragrant, stirring frequently to avoid burning.
Pour in the diced tomatoes with their juices and bring to a simmer.
Stir in heavy cream, grated Parmesan cheese, salt, black pepper, and crushed red pepper flakes.
Cook the sauce, stirring occasionally, for about 5 minutes until it thickens slightly.
Meanwhile, cook the tortellini according to package instructions until al dente, then drain.
Add the cooked tortellini to the skillet with the creamy tomato sauce and gently stir to coat evenly.
Remove from heat and stir in the chopped fresh basil leaves.
Serve immediately, garnished with additional Parmesan cheese if desired.