Cream butter and sugar with an electric mixture until light and fluffy. Heat coffee, water, and chocolate in a saucepan over low heat, stirring often until chocolate has melted entirely. Add coffee-chocolate mixture to the creamed sugar and butter. Beat in eggs, 1 at a time until incorporated, and then mix in vanilla extract. Combine flour, baking powder, salt, cinnamon and nutmeg in a mixing bowl and stir together with a fork until incorporated. Gradually beat the dry mixture into the wet mixture. Finally, fold in the raisins and walnuts.
Butter and lightly dust a bundt pan with flour. Pour batter into pan and bake about 45 to 50 minutes or until a sharp knife point inserted into the cake comes out clean. Let cool to room temperature on a rack before inverting. Dust with confectioners' sugar and serve.