Increase heat and bring to boil, stirring continuously for 10-15 minutes or until consistency is thick like syrup. Remove from heat, and chill until cold.Preheat oven to 325°F/160°C. Line a 13 x 9 x 2-inch metal baking pan with parchment paper, and brush with a little of the melted butter. Mix walnuts, pecans, almonds, cinnamon, all spice, and the remaining1/3 cup sugar in a medium bowl.Fold one sheet of phyllo pastry in half to form a 12 x 9-inch rectangle. Place folded sheet in prepared pan. Brush with melted butter. Repeat with four more folded sheets, brushing top of each with butter.Sprinkle half of nut mixture over the top of the pastry. Repeat with five more folded sheets, brushing the top of each with butter. Sprinkle remaining nut mixture over the top. Add five more folded sheets of pastry, again brushing the top of each with melted butter.Using a sharp knife, make seven diagonal cuts across the phyllo pastry, cutting through top layers only and spacing cuts evenly. Repeat in opposite direction, with cuts crossing in the middle to form a diamond pattern.
