mint-chocolate sandwich cookies

the goods:

1 and 1/4 cups all-purpose flour

1/2 teaspoon salt

1/2 cup (1 stick) unsalted butter, room temperature

2/3 cup granulated sugar

1 teaspoon pure vanilla extract

1 large egg

4 ounces semisweet chocolate, coarsely chopped

3/4 cup confectioners' sugar

1/4 teaspoon pure peppermint extract

Preheat oven to 325 degrees. In a small bowl, whisk together flour and salt. In a medium bowl, using an electric mixer, beat butter and granulated sugar on high, scraping down bowl as needed, until light and fluffy, 4 minutes. Add vanilla and beat to combine. Add egg and beat to combine. Add egg and beat to combine. With mixer on low, gradually add flour mixture and beat just until combined. Transfer dough to a quart-size zip-top bag; with scissors, snip a 3/4-inch hole in one corner (or use a pastry bag with a plain tip). Pipe cookies (3/4 by 2 inches), 1/2 inch apart, on a parchment-lined baking sheet. Chill until firm, 20 minutes.

Bake until cookies are light golden at edges, about 15 minutes. Transfer immediately to wire racks and let cool. Place chocolate in a medium heat-proof bowl set over (not in) a saucepan of simmering water. Stir until melted, 2 minutes. Remove bowl from pan. In another medium bowl, whisk together confectioners' sugar, peppermint extract, and 4 teaspoons water.

With a small offset spatula or table knife, spread chocolate on flat side of half the cookies and mint glaze on the other half. Sandwich cookie halves together.