Step 1

In a medium bowl, using an electric mixture, beat the butter and granulated sugar on medium-high speed until light and fluffy. Add the vanilla and egg and beat to combine. With mixer on low, gradually add the flour and salt and beat until just combined.

Step 2

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 about 24 cookies, 1/2 inch apart, onto two parchment-lined baking sheets. Chill until firm, 30 minutes.

Step 3

Preheat the oven to 325°F. Bake until cookies are light golden at edges, about 15 minutes, rotating sheets halfway through. Transfer to wire racks and let cool.

Step 4

Melt the chocolate in a glass bowl in the microwave for about 1 1/2 minutes, stirring every 30 seconds, until smooth. If desired, in another bowl whisk together confectioners’ sugar, peppermint extract and 3 to 4 teaspoons of water.

Step 5

With a small offset spatula, spread the melted chocolate on flat side of half the cookies and mint glaze on the other half (if using). Sandwich cookie halves together. Cookies can be stored in an airtight container up to 5 days.