HEAT oven to 350ºF.
PLACE tart shells on baking sheet. Mix Neufchatel, 1 Tbsp. sugar and 1 egg until blended; spoon into tart shells.
MIX pumpkin, spice, remaining sugar and egg until blended; spoon over Neufchatel layers in tart shells. Sprinkle with nuts.
BAKE 40 min. or until centers are set. Cool completely. Serve topped with COOL WHIP.