Thaw phyllo pastry leaves for 8 hours in refrigerator, if frozen. Unfold leaf sheets of phyllo so they lie flat. Cover with waxed paper, then a damp towel, to prevent them from drying out. Preheat oven to 325°F. In a medium bowl combine almonds, sugar, lemon peel, and cinnamon. Generously butter an 8- to 9-inch-square pan. Carefully fold 2 sheets of phyllo to fit pan; place in pan one at a time, brushing each with butter. Sprinkle about 3 tablespoons of the almond mixture over top sheet. Fold 1 sheet of phyllo to fit pan; brush with butter. Sprinkle evenly with another 3 tablespoons almond mixture. Continue to add layers, using 1 folded sheet of phyllo, a generous brushing of butter, and 3 to 4 tablespoons almond mixture for each, until nut mixture is used up (there should be about 10 nut-filled layers). Fold remaining 2 to 3 sheets of phyllo to fit pan. Place on top, brushing each, with butter before adding the next. With a very sharp knife, carefully cut diagonally across pan to make small diamond shapes--about 1 1/2 inches on a side--cutting all the way to bottom of pan. Pour on any remaining butter. Bake until golden brown (about 45 minutes). Pour warm Agave and Rose Water Syrup over top. Decorate each piece with an almond slice. Cool before serving.

AGAVE AND ROSE WATER SYRUP:
Combine sugar and the water in a 1 1/2-quart saucepan; bring to a boil, stirring. Mix in agave and cook until syrup boils again. Remove from heat; mix in rose water.