Take the pits out of the dates, add them to the syrup, pour in the whiskey. Boil until thickened. Cut the cozonacs into slices about 2 fingers thick.
Prepare a form with removable sides, lay it out with baking paper. Dip each cozonac slice in the warm syrup and arrange in the form.
To distribute them out well, if needed crumble some of the slices. Put dates and sprinkle walnuts over each layer of cozonac. Continue alternating cozonac and dates and walnuts until out of ingredients.
Press lightly to even it out and shape it. Pour on the remaining syrup and leave overnight in the fridge.