Mirror Cookies

These cookies are from a bakery (Boulangerie Guenaux) in the lakefront town of Morges, situated 20 miles from Geneva. What's so special about 'em? It's the gooey glazing on top. The bottom half of the cookie is intentionally overcooked (so it's crispy and not chewy) and the middle is filled with either raspberry or apricot jam. Many bakeries make these but very few seem to know the secret of overcooking the bottom half. No one can tell me why they are called Mirror cookies.