Heat olive oil in a large Dutch oven or heavy-bottomed pot over medium heat. Add finely diced onion and sauté for 4 to 5 minutes until soft and translucent.

Add minced garlic and tomato paste. Cook, stirring constantly, for 1 to 2 minutes until fragrant and the tomato paste turns deep brick red.

Pour in crushed San Marzano tomatoes, broth, dried oregano, red pepper flakes, salt, and black pepper. Stir well and bring to a gentle rolling boil over medium-high heat, then lower heat and simmer uncovered for 8 to 10 minutes to deepen flavors.

Add refrigerated cheese tortellini directly into the simmering soup broth. Cook for 3 to 4 minutes (or per package instructions) until the tortellini float to the top and are tender al dente.

Remove pot from heat to prevent curdling. Stir in heavy cream, freshly grated Parmigiano-Reggiano, and sliced fresh basil ribbons until cheese melts into a silky, velvety soup.

Ladle into warm bowls. Garnish with additional freshly shaved parmesan, cracked black pepper, fresh basil leaves, and serve immediately with warm crusty garlic bread.