Preheat oven to 375 degrees. Spray 12 muffin liners with cooking spray. Press 2 wonton wrappers into each muffin tin, (I laid them in the muffin tin in a criss cross pattern, so the corners evenly covered the entire muffin tin). Set aside.
Spray a medium pan with cooking spray. Sauté onions and garlic in pan over medium heat until onions are tender, stirring frequently. Turn off heat when done. Meanwhile, microwave the spinach in the microwave for 5 minutes. When spinach is done microwaving, place in the pan with the onions and garlic, and turn heat back to medium heat, sautéing the spinach in the pan until all of the excess moisture is out, then turn off heat.
Meanwhile, mix feta, parmesan, cottage cheese and egg in medium bowl. Add cooked onions, garlic, and spinach, and mix to combine.
Place a heaping teaspoon of the filling into the well of the wonton wrappers. Bake in the preheated oven for 20-25 minutes or until golden brown, (if the wonton wrappers are getting too brown for your liking, you can cover the muffin tin with foil in the last 5-10 minutes of baking).