In a large bowl, beat the cake mix, butter and egg until crumbly. Press onto the bottom of a greased 13x9-in. baking dish.
Place the sweet potatoes, cream cheese, 1/2 cup sugar, egg and pie spice in a food processor; cover and process until blended. Spread over crust.
Bake at 350° for 20-25 minutes or until center is almost set. Meanwhile, in a small bowl combine the sour cream, vanilla and remaining sugar. Spread over filling. Combine topping ingredients; sprinkle over top. Bake 5-8 minutes longer or just until set. Cool on a wire rack.
Refrigerate for at least 2 hours. Cut into bars. Refrigerate leftovers. Yield: 2 dozen.