In a bowl, beat eggs with a whisk or with an electric mixer until thick.
Beat in granulated sugar, lemon juice, flour, baking powder, and salt.
Pour over warm crust.
Bake until set, about 20 minutes.
Cool to room temperature, refrigerate about 1 hour.
Using the paper overhang as an aid, lift square from pan.
Sift remaining tablespoon confectioners' sugar over the top.
Cut into 16 squares.