Preheat oven to 225F. Line 2 baking sheets with parchment paper.
Whip the egg whites, cream of tartar, and salt in a large bowl until frothy, about one minute on high speed.
Gradually add the sugar 1-2 tablespoons at a time, waiting about 10-15 seconds between each addition. Add the vanilla extract.
Keep mixing on high until very stiff meringue forms (about 5 minutes) .
Place the meringue into a plastic piping bag fitted with the Sultan tip. Hold the bag about 1/2" above the parchment paper and squeeze the meringue.
Bake for 90-100 minutes.
Remove from the oven and allow to cool.
Bake The Cookies
Preheat oven to 350F.
Roll the dough between two pieces of parchment paper into a 1/4-inch thickness.
Use a cookie cutter slightly wider than the meringue cookies to cut the dough.
Place the cut dough over a baking sheet lined with parchment paper. Gently prick each cookie with a toothpick.If the dough is too sticky, place it back in the refrigerator to set for about 15 minutes.
Bake for 12-14 minutes. Remove from the oven and transfer onto a wire rack.
Assemble
Top each shortbread cookie with a meringue ring.
Fill a piping bag with the lemon curd, and pipe the curd at the center of each meringue. Serve immidietaly.
Notes
This recipe has three components, each taking its time to prepare and bake, so read the instructions carefully and plan ahead.
As assembled, the cookies should be stored in the refrigerator for up to five days. Take into consideration to the expiration of the lemon curd.
You can pipe the meringue over the cookies and use a kitchen torch to touch the top instead of baking the meringue.