Put the flour, sugar, nuts, baking powder, cinnamon and chocolate in a large mixing bowl and mix with a spoon.
Add melted butter to another bowl. Add the cold coffee and then the whole eggs and whisk everything together.
Mix the coffee-butter-egg mixture with the dry ingredients and stir well. Either pour the batter into a greased bundt pan or divide it into 12-20 (depending on size) muffin tins.
Baking time 60 minutes (Gugelhupf) or 25-30 minutes (muffins) at 180 °.
After cooling, you can cover the cake with chocolate glaze, powdered sugar or rum glaze.