Created by CookerKat on February 28, 2015
Step 1: Preheat oven to 350-degrees.
Step 2: In a large bowl, combine cake mix, water, buttermilk, oil, eggs, pudding mix. Beat with a mixer for about 2 minutes. Fold in sour cream. Pour batter into a greased 9x13 glass baking dish.
Step 3: In a smaller bowl, combine sugars, flour, cinnamon, and salt. Cut butter into small pieces and add to the sugar mixture. Mix together with a fork or pastry blender until crumbly. Stir in walnuts.
Step 4: Sprinkle HALF of the topping over the batter. Use a knife to swirl the mixture throughout the cake.
Step 5: Top evenly with remaining topping.
Step 6: Bake for 35-45 minutes or until a toothpick inserted into the center comes out clean.