Separate dough into long rectangles. Arrange crosswise in ungreased 10 X 15" jelly roll pan. Press dough evenly into pan, sealing perforations. Bake in a preheated 375 F oven until golden brown (about 14 minutes). Cool. Combine cream cheese, mustard, garlic salt and white pepper. Spread evenly over crust. Arrange tomatoes, cauliflower, broccoli, mushrooms, green and red pepper over crust. Sprinkle with green onion. Cut into small squares while pressing veggies with flat of hand. Refrigerate, covered loosely with plastic wrap, 1-2 hours.