The fresh lemon juice and zest in this simple glaze reinforces the lemon flavor of the cake.
Sift the confectioners’ sugar into a mixing bowl. Add the lemon juice and zest and whisk to mix. The glaze should be thick but pourable. (Add lemon juice if the glaze is too thick, confectioners’ sugar if too thin.) Spoon the glaze over the sponge cake and serve at once.