In a large saucepan or stockpot, cook sausage over medium-high heat, stirring frequently until thoroughly cooked and no longer pink. Add mushrooms, onion, carrots, celery and garlic; cook 10-12 minutes or until onion is translucent, stirring frequently. Transfer mixture to a large bowl; add remaining ingredients and stir well. Pour into a buttered 4-quart casserole.