Unsing electric mixer on medium-high speed, beat butter until fluffy, about 2 minutes. Beat in 2/3 Cup Sugar and lemon zest, then add egg and salt. Beat in flour 1 cup at a time. Divide dough into 2 pieces and form two disks Wrap in plastic wrap and chill overnight.
Preheat oven to 375 degrees. Line 2 baking sheets with parchment paper. On a lightly floured surface, roll out one dough disk to 1/4 inch thickness. Cut out cookies with a 2 1/2 inch cookie cutter. Sprinkle cookies with 1 1/2 teaspoons sugar. Repeat iwth other dough disk.
Bake cookie until golden aroung edges, 10 to 12 minutes. Place baking sheets on wire rack and cool cookies 5 minutes. Then transfer cookies to wire racks and cool completely.
Turn over half of the cookies, and spread 1 teaspoon jam on them. Top with the other half of the cookies.