Italian Almond Blood Orange Cookies Recipe

Name: Italian Almond Blood Orange Cookies Recipe
Ingredients: For Cookies:; 1/2 cup sliced blanched almonds, toasted and cooled (see note); 2 cups (about 10 ounces) all purpose flour; 1/2 teaspoon baking powder; 1/2 teaspoon salt; 16 tablespoons (2 sticks) unsalted butter, at room temperature; 1 cup (about 7 ounces) sugar; 1 egg yolk (white reserved); 1 teaspoon vanilla; 1 packed teaspoon blood orange zest from about 1 small blood orange; For Coating:; 1 egg white (reserved from egg above); 1 1/2 cups sliced blanched almonds; Confectioners sugar, for dusting