In a small saucepan, combine onion and water. Cook covered over medium heat 5 minutes. Do not drain. In a small saucepan, combine milk, cornstarch, and pepper; add to onion. Cook and stir constantly until thick and bubbly. Cook, stirring constantly 1 minute more. Add cheese, stir to melt. Add mushrooms. Cover and set aside.

In a large bowl, combine chicken, broccoli, pasta, and half of the mushroom cheese sauce. Mix well. Spoon into a medium casserole dish coated with non stick vegetable spray. Top with remaining mushroom cheese sauce. Bake at 350ºF. for 20 minutes. Makes 6 servings, 1 cup each.

(1 serving = 1/2 vegetable, 1 grain and 4 1/2 meat exchanges).