Preheat oven to 350 degrees. Gease and flour a 9x13 baking dish.
Combine cake mix with four eggs,2/3 cup oil, 2/3 cup milk and 1 tsp cinnamon. Pour into prepared cake pan. Bake for 25 minutes.
Sift 3 3/4 cups flour, white sugar and remaining tsp of cinnamon together. Add brown sugar, vanilla and 3 sticks of room temperature butter to flour mixture. Combined with pastry cutter or fork until coarse and crumbly. Top cake with this crumb mixture and continue to bake for 20 minutes.