In a large bowl , combine the cake mix, water, egg, beat on low speed for 30 seconds. Beat on medium for 2 minutes. Pour into an ungreased 8-in. square baking pan.
Bake at 350 degrees for 35-40 minutes or until a toothpick inserted near the center comes out clean. Cool for 10 minutes before removing from pan to a wire rack. When completely cooled, crumble the cake. Set aside 1/4 cup crumbs for garnish.
In a large bowl, whisk milk and pudding mixes for 2 minutes or until slightly thickened. Let stand for 2 minutes or until soft-set. Stir in pumpkin and spices until well blended.
In a trifle bowl or 3-1/2-qt glass serving bowl, layer a fourth of the cake crumbs, half of the pumpkin mixture, a fourth of the cake crumbs and half of the whipped topping. Repeat layers. Garnish with reserved cake crumbs. Serve immediately or refrigerate until serving.