Confectioners' sugar PREHEAT OVEN TO 160ºC . Beat the butter until light and soft, then beat in the sugar. Continue beating until very light. Stir in the almonds, then the flour. Scrape dough onto a piece of plastic wrap, flatten and wrap. Chill until firm, about 1 hour. Flour dough and surface very lightly and roll dough 1 cm thick. Cut into 3-to-4-inch rounds with a fluted cutter. Transfer to paper-lined pans and cut a 3 cm opening in half the rounds with a plain cutter. Paint the cut rounds with beaten egg and strew with the sliced almonds. Bake the bases about 15 minutes, keeping them very pale. Cool the bases. Combine the jam and water and bring to a boil over medium heat, stirring occasionally. Strain into another pan and simmer the glaze until sticky. Sift confectioners' sugar over the almond-coated bases. Paint the others with the glaze and adhere the sugared bases to them. Fill in the openings with more glaze.