Heat 1 tbsp olive oil in a large skillet over medium heat.
Add the Italian sausage, breaking it up with a spoon. Cook for 5-7 minutes until browned.
Remove excess grease if needed, but leave a little for flavor.
Add the onion to the pan and cook for 2 minutes until softened.
Stir in the garlic and red pepper flakes (if using), cooking for another 30 seconds until fragrant.
Add the orzo pasta to the skillet, stirring to coat it in the sausage and aromatics.
Pour in the chicken broth and bring to a simmer.
Stir in the cherry tomatoes and reduce heat to low.
Cover and let simmer for 10-12 minutes, stirring occasionally, until the orzo is tender and has absorbed most of the liquid.
Stir in the chopped spinach and cook for 1-2 minutes until wilted.
Remove from heat and add the Parmesan cheese, stirring until melted and creamy.
Taste and adjust seasoning with salt and black pepper if needed.
Garnish with extra Parmesan and fresh basil or parsley.
Serve warm and enjoy!