Step 1

Preheat oven to 325 degrees. In a small bowl, whisk together flour and salt. In a large bowl, beat butter, granulated sugar, and lemon zest on medium speed until pale and fluffy, about 10 minutes. Beat in eggs until combined. Gradually add flour mixture and beat on low until just combined. Slowly add milk and beat on medium until a dough forms, about 5 minutes.

Step 2

Transfer dough to a pastry bag fitted with a 1/2-inch round tip (such as Ateco #806). Pipe 1 1/2-inch rounds onto parchment-lined baking sheets. Bake, rotating sheets halfway through, until bottoms of cookies are pale golden, 16 to 18 minutes. Transfer sheets to wire racks; let cool completely.

Step 3

In a bowl, whisk together confectioners’ sugar and lemon juice until smooth. Using a pastry brush, brush glaze onto cookies. Sprinkle with sanding sugar. Let glaze harden, about 20 minutes. (Cookies can be stored in an airtight container at room temperature up to 3 days.)