Heat a bit of cooking oil in a large pot over medium-high heat. Add the chopped onion and minced garlic, cooking for about 1-2 minutes until the onion becomes soft and translucent. Add the ground turkey to the pot, using a spatula to break it apart as it cooks until it's browned and no longer pink. Drain any excess grease from the pot.
To the pot with the cooked turkey, add the uncooked orzo, Italian seasoning, salt, and pepper. Stir for about a minute to toast the pasta slightly. Pour in the tomato sauce, water, and heavy cream. Stir everything together until well combined.
Bring the mixture to a gentle boil, then reduce the heat to low-medium and let it simmer. Cook for about 10 minutes, stirring frequently to prevent the orzo from sticking to the bottom of the pot. The sauce will thicken and the orzo will become tender as it absorbs the liquid.
Remove the pot from the heat once the orzo is cooked through. Stir in the grated parmesan cheese and fresh baby spinach until the cheese is melted and the spinach has wilted. Cover the pot and let it sit for about 3-4 minutes to allow the flavors to meld. The sauce will continue to thicken as it cools.