Lemon Snowdrops

Directions

1. Preheat oven to 350°. Cream butter, confectioners' sugar and salt until light and fluffy, 5-7 minutes. Beat in extract. Gradually beat in flour. Shape teaspoons of dough into balls (if necessary, refrigerate dough, covered, until firm enough to shape). Place 1 in. apart on ungreased baking sheets; flatten slightly with bottom of a glass dipped in sugar. Bake until light brown, 10-12 minutes. Remove cookies from pans to wire racks to cool completely.
2. For filling, whisk together egg, sugar, lemon zest and lemon juice in a small heavy saucepan over medium-low heat until blended. Add butter; cook over medium heat, whisking constantly, until thickened and a thermometer reads at least 170°, about 20 minutes. Remove from heat immediately (do not allow to boil). Transfer to a small bowl; cool. Press plastic wrap onto surface of filling. Refrigerate until cold, about 1 hour.
3. To serve, spread lemon filling on half of cookies; cover with remaining cookies. If desired, dust with confectioners' sugar. Store leftovers in refrigerator.