1. Preheat the oven to 375ºF

2. Cut the squash in half lengthwise; remove and discard seeds. Put one half in a microwave safe dish (bowl side up) and fill with 1/4 up water. Top with the other half and microwave for 8 minutes, or until tender. Repeat until all the squash are cooked.

3. Heat butter and oil in a large saucepan over medium heat. Add onions and cook about 2 minutes. Stir in flour. Reduce heat to low and cook, stirring continually 3 - 4 minutes

4. Add milk and chicken broth and continue whisking, raising heat to medium-high until it comes to a boil and becomes smooth and thick, about 2 minutes stirring; season with salt and pepper.

5. Once it becomes thick, remove from heat, add cheddar cheese and mix well until cheese is melted. Adjust salt and pepper to taste, add cooked spaghetti squash and baby spinach, pour into a baking dish and sprinkle parmesan cheese on top. Bake until bubbly and golden 25 to 30 minutes.

Website with pictures: http://www.skinnytaste.com/2013/01/baked-spaghetti-squash-and-cheese.html#more