Heat the honey to boiling and allow to cool. Separate the eggs, reserving the whites. Beat the room temperature yolks with the butter until fluffy. Add the cooled honey and beat until well blended. Add the sugar and blend well. Sift the flour, baking powder, baking soda and cinnamon together, then sift again. Add to the honey mixture. Add the orange zest, juice, coffee and sour cream stirring until no dry flour shows. Whip the egg whites until stiff, then fold in a little of the whites, mixing well, then add the rest of the whites. Stir in the chopped nuts, if using them.
Pour into buttered and floured loaf pans, rapping them to even the batter. Bake in a preheated 160ºC . oven for about an hour. Do not open the oven door during the first 30 minutes of baking. When done, cool on wire racks for 10 minutes and then turn out to finish cooling. Wrap well in heavy duty aluminum foil and store in the refrigerator.