Filling: Juice of 1/2 lemon Start with the filling. Combine walnuts, sugar and cinnamon in a bowl. Melt the butter over medium heat, being careful not to burn. Allow the butter to settle for a few minutes. Skim the white foamy material from the top (clarify). With a pastry brush, butter the baking pan. Layer the pan with 12 individual sheets of filo, buttering each with pastry brush as they are placed. Be careful to cover the remaining sheets of filo with a slighlty damp twoel to avoid drying them out. Wet the walnut mixture with a small amount of butter and mix thoroughly. apply a layer of one-half of this mixture into the pan. Next apply five more layers of filo as before, on top of this. Layer next with remaining walnut mixture. Apply layers of filo dough on top of this until all is used. Chill for one-half hour. Cut rows of pastry length-wise and then cut diagonally to make diamond shapes. Pour remaining butter evenly over top. Pre-heat oven to 350 degrees F. and bake until golden brown (45min to 1 hour) Pour cooled syrup over the hot baklava until all is absorbed. Important: syrup must be cooled and baklava hot to avoid sogginess. To make syrup mix sugar, water, and lemon juice boil for 20 minutes. Remember to cool before pouring over pastry. Allow to cool to room temperature before eating.