Preheat oven to 175C. Lightly butter a 13" x 9" baking pan. Set aside. In a medium bowl, combine walnuts, cinnamon, allspice, nutmeg, cloves and sugar. Set aside. Stack filo pastry sheets on a flat surface. Trim to fit pan.Layer 12 filo sheets in baking pan, brushing each sheet with butter. Spread 1 cup of the nut mixture over layered filo sheets. Top with 8 more filo sheets, brushing each with butter. Spread with 1 cup nut mixture. Layer 8 more filo sheets, brushing each with butter. Spread the remaining nut mixture. Top with the remaining filo sheets, brushing each with butter. cut into 1-inch diamond shapes without removing from pan. Bake 30 minutes in preheated oven. Reduce heat to 200F (95C). Bake 30 minutes longer. Pour cooled syrup over warm pastry. Let stand several hours before serving.