Preheat oven to 350 degrees F (175 degrees C). Generously grease a 12 cup Bundt cake pan or a 9 or 10 inch tube pan.
Soak raisins in warm water until plump. Drain and dry. Chop coarsely. Mix with 1/3 cup dark brown sugar, cocoa, chocolate, cinnamon, and chopped nuts. You can also mince filling ingredients in a food processor for another texture.
Cream the unsalted butter with 1 cup brown sugar and white sugar until fluffy. Add cream cheese, and cream until blended. Add eggs and vanilla, and mix thoroughly. Blend in yogurt or sour cream. Fold in flour, salt, baking powder, soda. Mix well on low speed of mixer. Spread one third batter in prepared pan. Top with some of the filling mixture. Layer in this fashion until filling and batter are used up.
Bake until done, 50 to 60 minutes. Cool in pan 10 minutes before removing.