Lemon Drop Cookies

Position oven racks in upper and lower thirds of oven; preheat to 375°F. Line 2 large rimmed baking sheets with parchment paper.

Whisk all-purpose flour, whole-wheat flour, granulated sugar, baking powder and salt together in a large bowl until combined. Add butter and beat with an electric mixer on low speed until the butter is completely blended into the flour mixture, about 1 minute. Add milk, egg, lemon zest and vanilla; continue beating on low speed until blended, about 1 minute, scraping down sides of bowl as needed. Chill the dough, uncovered, for 30 minutes.

Using lightly floured hands, roll the dough into 24 (1-inch) balls and place 1 inch apart on the prepared baking sheets. Bake on the upper and lower oven racks until the edges are light golden and the tops are dry to the touch, 10 to 12 minutes. Cool on the pans for 5 minutes before transferring to wire racks to cool completely, about 30 minutes. (Reserve the baking sheets with parchment paper for glazing.)

Whisk confectioners' sugar and lemon juice together in a small bowl until smooth. Place the cooled cookies, still on the wire racks, over the parchment paper-lined baking sheets. Drizzle the glaze (about 2 teaspoons per cookie) over the tops of the cookies.