In a large heavy Dutch oven or soup pot, melt 2 tablespoons butter with 1 tablespoon olive oil over medium heat. Add the finely diced onion and cook for 4 to 5 minutes until soft, translucent, and fragrant.

Add the minced garlic, Italian seasoning, and red pepper flakes. Cook for 1 minute until highly aromatic.

Stir in the tomato paste, cooking and stirring constantly for 2 minutes until it deepens into a rich brick-red color and coats the bottom of the pot.

Pour in the crushed San Marzano tomatoes and vegetable broth. Whisk well to combine and dissolve any caramelized tomato paste from the bottom.

Season with 1 teaspoon fine sea salt and 1/2 teaspoon black pepper. Bring the soup to a gentle boil over medium-high heat, then reduce heat to medium-low, cover partially, and let simmer for 10 minutes to allow the tomato sweetness to develop.

Uncover the pot and drop in the fresh refrigerated cheese tortellini. Simmer gently for 3 to 4 minutes until the pasta puffs up and floats to the top (al dente).

Lower heat to low. Stir in the heavy whipping cream, freshly grated Parmigiano-Reggiano, and chopped baby spinach. Stir gently for 1 to 2 minutes until the spinach is wilted and bright green, and the cheese has melted completely into a velvety, creamy broth.

Remove from heat immediately to prevent the tortellini from overcooking. Taste and adjust salt or black pepper as desired.

Ladle into deep ceramic bowls. Finish with an extra swirl of heavy cream, a generous shower of grated parmesan, fresh basil ribbons, and a crack of black pepper. Serve warm with crusty garlic bread or grilled cheese!