Blueberry Refrigerator Pie

HEAT oven to 350°F.

RESERVE 1 Tbsp. butter. Melt remaining butter; mix with wafer crumbs. Press onto bottom and up side of 9-inch tart pan with removable bottom. Bake 10 min. or until golden brown.

MEANWHILE, combine 1-1/2 cups blueberries, 1/2 cup sugar and 1 Tbsp. cold water in saucepan. Bring to boil, stirring constantly. Dissolve cornstarch in 3 Tbsp. of the remaining cold water; whisk into blueberry mixture. Simmer on low heat 2 min. or until thickened, stirring constantly. Remove from heat. Add reserved butter; stir until melted. Reserve 1/2 tsp. lemon zest and 1 tsp. juice; stir remaining zest and juice into blueberry mixture. Pour into crust.

ADD boiling water to gelatin mix in medium bowl; stir 2 min. until completely dissolved. Add enough ice to remaining 1/2 cup cold water to measure 1 cup. Add to gelatin; stir until slightly thickened. Remove any unmelted ice. Whisk 1 cup COOL WHIP into gelatin. Refrigerate 15 min. or until mixture is thick enough to mound. Stir in 1-1/2 cups of the remaining blueberries; spoon over layer in crust.

REFRIGERATE 4 hours or until firm. Top with remaining COOL WHIP. Toss remaining blueberries with reserved lemon zest, juice and sugar; spoon over pie.