Preheat oven to 375. Foil line pan. Cut squash in half rub with olive oil salt and pepper.
Place onion quarters under squash and bake for 35 mins
Sauté 1/4 small copped Onion, chopped yellow squash and 3 cloves chopped garlic for 3-5 mins. Add sausage and 1tsp celery seed. Brown.
Crush in tomatoes and basil. Warm on low for 5 mins
Mix sour cream, egg and parm
Cream into sausage mixture
Spoon into squash and bake for 15 mins on 350 sprinkle with cheese and bake for 3-5 more mins. Let rest 10 mins before serving.
Serve with crusty bread and enjoy!