HEAT oven to 350°F.
MIX wafer crumbs and melted butter; press onto bottom and up side of 9-inch tart pan with removable bottom. Bake 10 min. or until golden brown; cool.
MEANWHILE, combine 1-1/2 cups blueberries, sugar and 2 Tbsp. water in large saucepan. Bring to boil on medium-high heat, stirring constantly. Dissolve cornstarch in remaining water; whisk into blueberry mixture. Simmer on low heat 2 min. or until thickened, stirring constantly. Remove from heat. Add butter, zest and juice; stir until butter is melted. Stir in 3 cups of the remaining blueberries.
POUR blueberry mixture into crust; top with remaining blueberries. Refrigerate 3 hours or until firm. Top with Cool Whip. Remove side of pan before serving.
serving size = 1 piece (138 g)