In a medium bowl, combine 1 cup of all-purpose flour, ½ cup of powdered sugar, ½ cup of cold unsalted butter, and a pinch of salt. Mix until crumbly and chill for 15 minutes.

Preheat oven to 350°F (175°C). Press the chilled dough onto a parchment-lined baking sheet in 2-inch circles, about ¼ inch thick, and create an indentation for the filling. Bake for 12-15 minutes until edges are golden.

Prepare the lemon filling by mixing ⅓ cup lemon juice, ¾ cup granulated sugar, 1 egg yolk, 1 tablespoon cornstarch, and zest in a saucepan over medium heat until thickened, about 5 minutes.

In a clean bowl, beat 2 egg whites and ¼ teaspoon cream of tartar until soft peaks form. Gradually add ½ cup granulated sugar until stiff peaks form.

Spoon the lemon filling into each cookie indentation, then pipe or dollop the meringue over each, covering completely.

Lower oven to 200°F (90°C) and bake the assembled cookies for 40-50 minutes until the meringue is set but not browned.

Turn off the oven and let cookies cool inside for 30 minutes, then remove them and cool on a wire rack.