Combine water and sugar in a small saucepan with a whisk.
Bring to a boil and boil until the sugar dissolves and the syrup turns clear.
Make this glaze before you begin making cookies, and allow it to cool to slightly above room temperature while you make and bake your cookies. When the cookies and the syrup are cool, brush each cookie with a very thin coat of glaze and sprinkle on decorations or large-crystal sugar.
Allow glaze to dry for at least an hour before stacking cookies. Thin glaze will dry faster than a thick coat of glaze.