This recipe (from Allrecipes.com) appeared in Mmm! Mmm! Melt–in–Your–Mouth Good! on 08 Dec 2008
1 cup butter
1/2 cup confectioners’ sugar plus more for dusting
2 cups all–purpose flour
1 teaspoon lemon zest
1/2 teaspoon salt
1 egg, beaten
2/3 cup sugar
1–1/2 teaspoons lemon zest
3 tablespoons lemon juice
1–1/2 tablespoons butter
To make cookie dough, cream together butter and confectioners’ sugar in a medium bowl until light. Stir in the flour, lemon zest and salt. Cover bowl and chill dough for about 1 hour.
Preheat oven to 400° F.
Flatten teaspoonfuls of dough onto cookie sheets and bake for 5–8 minutes until light brown. Remove from baking sheets to cool on racks.
To make the filling, combine the beaten egg, sugar, lemon zest, lemon juice and butter in the top of a double boiler. Stir until thick (15–30 minutes). Sandwich the cookies with 1 teaspoon of filling. Dust tops of the cookies with confectioners’ sugar.
To make thumbprint cookies, roll dough into 1–inch balls. Press thumb into tops until small indentations are created. Bake until slightly browned (5–8 minutes). Cool on racks.
Fill cooled thumbprints with lemon filling. Dust the tops with confectioners’ sugar.