Mix flour, powdered sugar and butter. Press into a 9x13-inch pan. Bake at 350 F 20 to 30 minutes. Cool.
Cream cheese filling
Mix cream cheese until light. Add sugar and cream well. Fold in whipped topping. Spread over cooled crust and chill.
Sprinkle gelatin over cold water to soften. Add boiling water, sugar and salt, stir until thoroughly dissolved. Add lemon juice. Stir to combine. Cool. Add mangoes and chill until gelatin begins to set. Pour over cream cheese mixture and chill.