6 Tablespoons cool unsalted butter, cut into pieces
1 ¼ cups confectioners’ sugar
Scant ½ cup egg whites (from about 4 eggs)
1 teaspoon pure vanilla extract
1 teaspoon pure lemon extract
¾ cup all-purpose flour
1 egg white
About 2 cups confectioners’ sugar
A few drops of mint extract
4 ounces semisweet chocolate
Heat the oven to 350 degrees.
Make the cookie dough: Cream the butter until smooth in a mixer fitted with a paddle attachment. Mix in the sugar. A little at a time, mix in the egg whites, then add the vanilla and lemon extracts. Add the flour and mix just until incorporated. Transfer the dough to the pastry bag with a plain ¼ inch tip.
Prepare two cookies sheets with parchment paper. Pipe 1-inch long sections of dough onto the sheet pans, spacing them 2 inches apart (the will spread sideways). Bake until golden on top and brown around the edges, about 10 minutes. Let the cookies cool on the pan.
Make the mint glaze: Whisk the egg white with 1 ½ cups of the confectioners’ sugar until smooth. Whisk in more sugar a little at a time, just until you have a thick, smooth glaze. And mint extract to taste.
Make the chocolate glaze: Melt the chocolate. Spread the flat sides of half of the cookies with chocolate. Spread the flat sides of the remaining cookies with mint glaze. Sandwich together and set on a clean sheet pan. Let the cookies sit at room temperature until firm, at least 1 hour.