BEAT butter and sugar in a large bowl, using an electric mixer on medium, until fluffy. Beat in egg yolk and almond extract. Gradually beat in almond mixture until just combined.
WRAP in plastic wrap, pressing into a flat disc. Refrigerate until firm, 30 min.
PREHEAT oven to 375F. Line 2 baking sheets with parchment.
SCOOP dough into heaping 1-tbsp balls. Roll each ball into a 3-in. log with tapered ends, then turn both ends inward to form a crescent.
ARRANGE on baking sheets and chill until firm, 15 min. Bake until lightly browned on edges, about 11 min. Let cool slightly. Gently dip warm cookies in icing sugar. Return to baking sheet to cool completely. Sift remaining icing sugar over cookies. Cookies will keep well in a covered container at room temperature for up to 1 week.