Preheat the oven to 190°C/375°F/Gas mark 5
Put the water in a medium saucepan and add the dates, walnuts and sugar. Cook until 'sludge' consistency is reached, about 15-20 minutes over medium heat. Cool for 15 minutes.
Cream the butter and sugar and vanilla together. Add yoghurt and beat. Sift together the baking soda, baking powder and flour. Add the 'sludge' to the cream mixture, beat well. Slowly add sifted ingredients and the oatmeal. Allow to sit for about 5 minutes.
Drop by spoonsful onto a greased cookie sheet and bake for about 10-15 minutes, or until a light brown on top. Let cool slightly on the tray, and then transfer to cooling racks to cool completely.
