¼tspcoarse Kosher salt(if using table salt, use half the amount)
⅔cupcold unsalted butter (about 10 1/2 tablespoons)cut into 10 pieces
1tsplemon paste(or lemon extract)
zest of 1 small lemon
2 ½tbspwhole milk
Icing
1 ½cupspowdered sugar
3 ½ - 4tbsplemon juice
fresh lemon zest and coarse sparkling sugar,for garnish
Instructions
Making the Dough
In your food processor, pulse the flour, powdered sugar and salt until combined.With the processor running, drop in the pieces of butter, one at at time, pulsing a few times until the butter is evenly distributed, and the dough is moistened and crumbly.Add the lemon paste/extract, lemon zest and the milk, then process until the dough starts to stick together.
Dump the dough out onto a clean counter and use your hands to finish bringing the dough together, kneading in any stray bits of flour. The dough should be soft, smooth and supple.
Shape the dough into a log, measuring approximately 8 inches long and 2 inches in diameter. Wrap the log of dough in wax paper, and twist the ends of the paper, then wrap in plastic wrap. Refrigerate for 2-3 hours, or overnight, until firm enough to be sliced into cookies.
Baking the Cookies
Preheat the oven to 350 F, and position a rack in the center of the oven. Line a large baking sheet with parchment baking paper.
Unwrap the log of chilled dough, and use a sharp chef's knife to cut slices about 1/4 inch thick. Place the cookies 1 inch apart on the baking sheet.
Bake the cookies for about 11 1/2 - 12 minutes. The tops should be a very pale golden with no dark browning, and you should see tiny flaky layers around the edges.
Cool the cookies for 5 minutes on the pan, then very gently transfer them to a cooling rack to cool completely.
Icing the Cookies
Whisk together the powdered sugar and lemon juice until smooth and drizzly.
Place the cooling rack over your baking sheet to catch the icing drips, and use a spoon to drizzle the icing over the cookies.
Wait a few minutes for the icing to set, then sprinkle with coarse sparkling sugar and fresh lemon zest. The icing will dry to the touch within an hour, but it does stay soft underneath, so if you stack the cookies, the icing will get smushed and won't look as pretty.
Notes
Making the Dough without a Food Processor: If you don't have a food processor, you'll need a large bowl and a pastry cutter. In the bowl, combine the flour, sugar and salt. Scatter with the cold butter pieces and use the pastry cutter to cut the butter in until very finely cut and evenly distributed. Drizzle with the vanilla and milk, then use your hands to work the liquid into the dry ingredients until it forms into a soft dough.
Storing the Baked Cookies: The baked cookies should be cooled completely then stored in an airtight container for up to 5 days. If you won't be frosting and decorating them immediately, freeze the cookies in an airtight container for 3-6 months.