Preheat oven to 350 degrees. butter a 23 cm bundt pan. Sift together cocoa, flour, baking powder and salt. Set aside. Cream together softened butter and sugar using an electric mixer on medium speed. Beat until light and fluffy. With mixer on medium, add eggs, one at a time. Beat in vanilla. Mix together buttermilk and water. Fold cocoa mixture and buttermilk mixture alternately into butter mixture. Stir in hazelnuts. Spread batter in pan. Bake 50 minutes or until a skewer inserted in center comes out clean. Cool cake. Invert onto a rack.
Coffee-cinnamon Cream: Mix together cream cheese, whipping cream, vanilla, instant coffee, cinnamon, sugar and salt. With electric mixer on high speed beat until mixture holds its shape. Refrigerate until ready to use.
Serve slices of pound cake with cream mixture.