There are several ways to handle such a big squash. 1) you can peel it and take the seeds out. Cut it up and cook it with garlic and salt like you would potatoes. Then when it is fork tender you can make a white sauce that is laced with garlic, parsley and any other herbs you are really fond of. That is how eastern europeons used them in the last generation.
2) you can cut it in half lengthwise and scoop out the seeds. Stuff it with a mixture of ground beef and or turkey mixed with rice and garlic. Cover with tomato soup, sauce or ketchup. Place in a large sheet pan and bake covered or uncovered until the squash is fork tender. Serve with salad and mashed potatoes. I made that one up when I was in college and suddenly found I was going to have 10 guests over for dinner. They loved it and it has become a family staple, for those inevitable too large squash.