Preheat oven to 325 degrees.  Grease a 9" by 13" cake pan.  Combine the Topping & Filling ingredients in a bowl.  Mix well and set aside.

In a large bowl, beat the butter until creamy.  Add the sugar and beat until light and fluffy.  Add the eggs one at a time beating well after each.  Combine the dry ingredients in a sifter and sift into the creamed mixture, alternating with the sour cream and mixing after each addition.  Stir in the vanilla.  Pour half the batter into the cake pan.  Cover with half the Topping and Filling.  Pour the remaining batter over the filling (pour in the middle and spread by gently pushing the batter towards the edges with a spoon).  Top with the remaining topping.  Bake until you can pierce the center with a toothpick and remove it clean (about 45 minutes).