In a medium saucepan, heat the olive oil over medium heat. Add the diced onion and sauté until translucent, about 3-4 minutes.
Stir in the minced garlic and red pepper flakes (if using), cooking for an additional 1-2 minutes until fragrant.
Add the orzo to the saucepan, stirring to coat it in the oil. Toast the orzo for about 1-2 minutes, stirring frequently.
Pour in the vegetable broth and bring to a boil. Reduce the heat to a simmer, cover, and cook for about 10-12 minutes, or until the orzo is tender and has absorbed most of the liquid.
Stir in the chopped spinach and cook for 2-3 minutes until the spinach is wilted.
Lower the heat and stir in the heavy cream and grated Parmesan cheese, mixing until the cheese is melted and the sauce is creamy. Season with salt and pepper to taste.
Remove from heat and let rest for a minute or two to thicken up.
Notes
Serve in bowls, garnished with additional Parmesan cheese and fresh basil leaves.