Preheat the oven to 350F. Lightly grease a 2 quart baking dish.
Coat a large skillet with cooking spray and, over medium heat sauté the mushrooms, stirring occasionally, until the mushrooms are nice and golden, about 5-7 minutes.
Add the onions to the pan and cook, stirring occasionally, until translucent and tender, about 4-5 minutes. Add spinach and cook until wilted, about 2 minutes. Remove from the heat. Add the rice, quinoa and hazelnuts to the skillet and stir to combine.
In a large bowl, whisk together the egg, egg whites, cottage cheese, plain yogurt, salt and pepper, until smooth.
Add in the rice mixture and stir gently until well blended. Transfer to reserved baking dish.
Sprinkle the cheddar cheese over the top, cover the dish with foil and bake for 30 minutes. Remove the foil and bake for another 20-30 minutes, until the top is lightly browned.
Top with freshly grated parmesan cheese, if desired.