Combine cake mix, egg, sour cream, pumpkin puree melted butter, spices and vanilla and mix until combined. The batter will be slightly lumpy.
Spread half the cake batter in the bottom of the greased baking dish. The batter will be thick so just do you best. Sprinkle with half of the crumble mixture. Grease a rubber spatula and gently spread the remaining batter over the crumble ( again it doesn't need to be perfect) Top with remaining crumble.
Bake for 30-35 minutes until an inserted toothpick comes out clean. Serve warm.