Prepare the dough: In a large bowl, whisk together flour, powdered sugar, and salt. Cut in the chilled butter until the mixture resembles coarse crumbs. Press dough into a ball, wrap in plastic wrap, and refrigerate for 30 minutes.

Roll out dough: Preheat oven to 350°F (175°C). Roll the dough out to about 1/8-inch thickness on a floured surface. Cut into circles using a cookie cutter.

Bake the cookies: Place the dough circles on a baking sheet lined with parchment paper and bake for 8-10 minutes, or until lightly golden. Let cool completely on the baking sheet.

Make the lemon filling: In a saucepan, whisk together lemon juice, granulated sugar, egg yolk, cornstarch, and lemon zest. Cook over medium heat, stirring constantly, until thickened. Remove from heat and let cool.

Make the meringue: Beat egg whites with cream of tartar using an electric mixer until foamy. Gradually add granulated sugar and beat until stiff peaks form.

Assemble the cookies: Spoon lemon filling onto each cooled cookie and top with meringue.

Broil: Place the cookies under the broiler for 1-2 minutes until the meringue is lightly golden. Let cool completely before serving.