PREHEAT oven to 350° F. Grease 13 x 9-inch baking pan.
COMBINE pumpkin pie mix, evaporated milk and eggs in large bowl. Pour into prepared pan.
COMBINE cake mix, melted butter and nuts in large bowl until crumbly (clean hands may be used). Sprinkle over filling.
BAKE for 50 to 55 minutes or until golden brown on top. Cool completely in pan on wire rack. Cut into bars. Top each serving with whipped topping, if desired.