Heat oven to 400°F. Spray large cookie sheet or 16-inch pizza pan with CRISCO® Original No-Stick Cooking Spray. Unroll pizza crust dough on cookie sheet; press dough into 17x12-inch rectangle. Bake 7 to 9 minutes or just until crust is light golden brown.
Meanwhile, in large bowl, beat cream cheese, mayonnaise, mustard and garlic salt with electric mixer on medium speed until smooth. Stir in water chestnuts and crabmeat, being careful to break up crabmeat as little as possible.
Spread crabmeat mixture over partially baked crust to within 1 inch of edges. Spoon small spoonfuls of pineapple topping evenly over crabmeat mixture; spread evenly. Sprinkle with Monterey Jack cheese and onions.
Bake 12 to 15 minutes longer or until cheese is bubbly and crust is golden brown. Cool 5 to 10 minutes before cutting.