Heat olive oil in a large deep skillet or Dutch oven over medium heat.
Add the Italian turkey sausage, breaking it up with a spoon, and cook until browned and cooked through, about 5-7 minutes.
Add the diced onion and cook until softened, about 3 minutes.
Stir in the minced garlic and cook for 1 minute until fragrant.
Add the orzo pasta to the pot and stir to coat it in the oil and sausage mixture.
Pour in the diced tomatoes with their juice and the chicken broth.
Add the dried oregano, dried basil, crushed red pepper flakes, and season with salt and pepper to taste.
Bring the mixture to a boil, then reduce heat to a simmer.
Cover and cook for 10 minutes, stirring occasionally to prevent sticking.
Remove the lid and stir in the fresh baby spinach leaves until wilted, about 2 minutes.
Continue cooking uncovered for another 5 minutes or until the orzo is tender and most of the liquid is absorbed.
Taste and adjust seasoning with additional salt and pepper if needed.
Serve hot, topped with grated Parmesan cheese.