Bring a large pot of salted water to a boil. Cook the tortellini according to package instructions. Reserve ½ cup pasta water, then drain.
In a large skillet over medium heat, add olive oil, butter, and 1 Tablespoon of the reserved sun-dried tomato oil.
Add the garlic and cook for about 30 seconds, just until fragrant.
Stir in the chopped sun-dried tomatoes and Calabrian chili paste. Cook for 1–2 minutes to develop the flavor.
Pour in the heavy cream and bring to a gentle simmer. Let it cook for 3–4 minutes until slightly thickened.
Stir in the grated Parmesan cheese until smooth and creamy.
Add the fresh spinach and stir until just wilted.
Add the cooked tortellini to the skillet and toss gently to coat. Add a splash of reserved pasta water if needed to loosen the sauce.
Reduce the heat to low. Stir in the torn basil, season with salt and freshly ground black pepper to taste, and serve immediately.
