Preheat oven to 350 degrees. In a mixing bowl combine the cake mix,sour cream,oil,sugar,water and eggs. Beat until smooth and set aside.
In a separate bowl,combine the walnuts,brown sugar,cinnamon,melted butter,milk,and vannilla mixing well.
Pour half the cake mixture in to a greased and floured bundt pan then add nut mixture. Then top with the rest of cake mixture. Bake for 45-55 minutes or until done. cool in pan before transfering onto cake plate.