Process pistachios in food processor 1 minute, or until finely ground. Transfer to bowl, and set aside.

Cream butter and sugar in food processor 30 seconds, or until fluffy. Add egg and lemon juice; pulse 15 seconds, or until combined. Scrape down. Add pistachios, flour, lemon zest, baking powder, and salt. Pulse 15 seconds more, or until combined and dough starts to clump together. Divide dough in half, flatten into 2 disks, wrap in plastic wrap, and refrigerate 1 hour, or until firm.

Preheat oven to 350 degrees F. Roll out 1 dough disk on sheet of lightly floured parchment paper, to about 1/8-inch thick. Transfer parchment and cookie dough onto cookie sheet and cover with plastic wrap. Place in freezer 5 to 8 minutes to firm up.

Cut out cookies with 2-inch cutter, and place 1-inch apart on parchment paper-lined baking sheets. Reroll scraps, and repeat. Bake 12 minutes, or until edges are golden. Transfer to wire rack to cool. Repeat with remaining dough disk.

Spread 1 teaspoon preserves on each of 24 cookies. Top with remaining cookies.