1Move oven rack to lowest position. Heat oven to 450°F. Spray 12-inch pizza pan with cooking spray.
2In medium bowl, stir Bisquick mix, hot water and 1/4 cup of the spinach dip with fork until soft dough forms; beat vigorously 20 strokes. Press dough in pizza pan, using fingers dipped in Bisquick mix; pinch edge to form 1/2-inch rim. Bake 7 minutes.
3Spread remaining 1/2 cup spinach dip over partially baked crust. Sprinkle with chicken, tomato and mushrooms. Sprinkle with cheese.
4Bake 12 to 15 minutes or until crust is brown and cheese is melted.