In medium saucepan, combine broccoli, beans, corn, and celery, and add enough water to cover the vegetables (if using spinach instead of broccoli: cook seperately according to package directions so you can squeeze out the excess water; then combine with other veggies).
Cover pan, and bring to a boil.
Reduce heat to medium-low; simmer until vegetables are tender-crisp (8 minutes).
Remove from heat and set aside.
Preheat oven to 350°F.
On a lightly floured surface, roll pastry out to a 12"x8" rectangle.
Bake for 11-15 minutes on ungreased baking sheet; then set aside.
Thin the cheese soup by mixing it with the milk.
In large saucepan, melt butter over medium-high heat.
Sauté chicken, garlic, onion, and mushrooms until onion and mushrooms are tender, stirring constantly (5 minutes).