MAKES ABOUT 4 1/2 DOZEN
Vanilla sugar may be made easily at home: put a few vanilla beans in a jar, fill it with confectioners' sugar, and let infuse for at least a week.
2 1/4 cups flour
2 cups confectioners' sugar
1/2 cup blanched almonds, finely ground
3 9-gram packets vanilla sugar
1/2 lb. (2 sticks) cold unsalted butter,
cut into small pieces
1/4 tsp. lemon extract
1 tbsp. milk
1. Combine flour, 3/4 cup of the confectioners' sugar, almonds, 2 of the vanilla sugar packets, and salt on a clean surface, shape into a mound, then make a well in the center. Add butter and lemon extract to well. Using your fingers, work flour–nut mixture into butter until dough resembles coarse meal. Sprinkle milk over dough, knead until smooth, and shape into a ball. Cover with plastic wrap and refrigerate for 1 hour.
2. Preheat oven to 350°. Sift remaining confectioners' sugar and vanilla sugar into a medium bowl and set aside. Divide dough into 16 equal pieces. Using your hands, roll each piece of dough out on a clean surface into 3/4"-thick ropes. Cut ropes crosswise into 2 1/2" pieces, then gently pinch ends to round off edges. Shape pieces of dough into small crescents and transfer to parchment paper–lined baking sheets. Bake until golden around edges, 12–14 minutes. Allow cookies to cool for 1 minute, then transfer a few at a time to bowl of sugar and coat well. Transfer cookies to a rack to let cool completely. Cookies may be stored in airtight containers for up to 1 week.