Mix together brown sugar, flour, cinnamon and instant coffee powder. Blend in butter until crumbly. Stir in nuts. (I prepare the topping in the food processor.) Set aside.

Mix boiling water and coffee powder together. Put in the refrigerator to cool while you prepare the batter.

In mixer bowl, cream together butter and sugar. Beat in eggs one at a time. Stir in vanilla.

In a small bowl mix together the flour, baking powder, baking soda and salt.

Combine sour cream with cooled coffee.

Add flour mixture and sour cream mixture alternately to the creamed ingredients, mixing after each addition.

Spread half of the cake batter in a greased 9 inch tube cake pan. Sprinkle half of the topping over the batter. Spread the remaining batter, and top with the remaining topping.

Bake at 350 degrees F. for 55 to 60 minutes. Cool in the pan for about 10 minutes, then run a knife around the sides and remove cake from pan.