Instructions

In a large bowl, with a mixer on medium, beat 1 cup butter and sugar until smooth. Add egg yolk, liqueur/extract, and orange peel. Beat until well blended.
In another bowl, mix 2 cups flour, baking powder, and salt. Add to butter mixture; stir to mix, then beat until well blended. Gather dough into a ball, divide in half, and flatten each portion into a disk; wrap each tightly in plastic wrap and freeze until firm enough to roll without sticking, about 30 minutes.
Unwrap dough. On a lightly floured surface, with a floured rolling pin, roll ane disk at a time to about 1/4 inch thickness. With a floured, 2-inch round cutter, cutout cookies. Place about 2 inches apart on baking sheets. Gather excess dough into a ball, reroll, and cut out remaining cookies.
In a small bowl, beat egg white with 1 t water to blend. Brush cookies with mixture and arrange about 1/2 teaspoon (5 slices) sliced almonds on each. Bake cookies in a 325 degree oven until lightly browned, about 15 minutes. Let cool on sheets 5 minutes, then transfer to racks to cool completely.