Half the squash and scoop out and discard the seeds. Scoop out the pulp and chop finely. In a heavy skillet, saute chopped onions, minced garlic and sliced mushrooms until the mushrooms release their liquid and begin to color a bit. Add the spinach and stir until it wilts. Add the halved cherry tomatoes, chopped parsley and salt and pepper to taste. Stuff each squash half with the vegetable mixture and top with fresh garlic croutons and crumbled feta cheese and bake at 350 F for 20 to 25 minutes until hot and bubbly.