Preheat oven to 350 degrees F. Lightly coat a 9×13" baking dish cooking spray.
Heat olive oil in large skillet, add onions, cook for a few minutes. Add turkey cook until brown.
Stir in half of salt & pepper, and all mushrooms, zucchini, garlic, oregano, and red pepper flakes.
Cook until vegetables start to soften, about 3-4 minutes. Don't over cook.
Stir in crushed tomatoes and remaining salt, to taste, and pepper. We don't add salt, there is enough sodium in the other ingredients for us. Bring mixture to a boil, reduce heat and simmer for 10 minutes, stirring occasionally.
Add rice and 1/4 cup Parmesan cheese, and 3 tbsp parsley.
Stir together.
Transfer mixture to prepared baking dish. Sprinkle remainder of Parmesan cheese on top of dish. We did not add the cheese on top.
Cook about 20 minutes until casserole is bubbling and cheese is starting to brown.
