Preheat oven to 450. On one baking sheet, place squash cut side down. Toss brussels sprouts with garlic and 2 tsp oil. On second baking sheet, arrange brussels sprouts, whole celery, and chopped onion. Place squash on bottom rack and other vegetables on top rack. Roast veggies for 20-25 min until they turn a golden brown color. The squash will be done when it can easily be pricked with a fork. It should be soft but not mushy. When done, set aside to cool.
While the veggies are roasting, saute sausage in 1 tbsp oil on medium high heat in a large stockpot until cooked through. Remove pan from heat. Carefully chop celery, peel squash and cut into cubes. Add all roasted veggies to turkey as well as remaining ingredients. Toss to mix well. Place mixture in two greased casserole dishes. Top with dollops of goat cheese. Bake for 30 min on 350.