These are a mainstay of almost every pastry shop in Switzerland. These are a sweet cookie, as anything meringue-based tends to be. In the past I always used unsweetened chocolate to make them, but I once accidentally substituted some premium bittersweet chocolate and the cookies were already in the oven before I realized my mistake. Though still sweet (the sugar in the chocolate didn’t really make them appreciably sweeter), they had a much more complex flavor because of the superior quality of the chocolate. An S shape is traditional for these, but of course you may pipe them in any shape you wish.

Makes 40 to 50 cookies, depending on the size they’re piped

4 large egg whites

Pinch of salt

1 1/4 cups sugar

5 ounces bittersweet chocolate (70 to 75% cocoa solids), melted and slightly cooled

Two cookie sheets or jelly-roll pans lined with parchment paper

Half-fill a saucepan on which your mixer bowl will fit without having more than 2 inches inside the pan. Bring the water to a boil over low heat.
Place the egg whites in the bowl of an electric mixer and whisk by hand to break them up. Whisk in the salt and sugar.
Set the bowl over the pan of water so only a small part of the bottom is submerged and whisk gently just to keep the mixture moving so that it doesn’t set on the bottom; whisking too vigorously can tighten the mixture and prevent the sugar from melting. Continue whisking until the egg whites are hot (130˚F) and the sugar has dissolved. Lift the whisk and let a little of the mixture run over a fingertip to test temperature and smoothness. While heating the mixture, occasionally scrape the side of the bowl with a rubber spatula to keep sugar from accumulating there.
Place the bowl on the mixer and whip with the whisk attachment on medium-high speed until the meringue is very increased in volume and looks like marshmallow, about 3 minutes. Stop whipping when the side of the bowl feels just slightly warm.
Use a large rubber spatula to fold the chocolate into the meringue. Be careful not to fold so much that the meringue liquefies from contact with the fat in the chocolate. If there are a few streaks of white remaining, ignore them.
Half-fill a pastry bag fitted with a 1/2-inch star tip (Ateco #824) and pipe the meringue onto the pans in “S” shapes: Hold the bag almost perpendicular to the pan and inclined slightly toward you, with the end of the tube close to the pan. Start to squeeze out an “S” shape; when you come to the end, pull away parallel to the pan, not straight upward, to avoid leaving a point.
After piping the cookies, let them dry at room temperature for a couple of hours so they retain their shape better and they form the characteristic “foot” at the bottom (see the photograph).
About 20 minutes before your ready to bake the cookies, set racks in the upper and lower thirds of the oven and preheat to 350˚F.
Bake the cookies until they are matte looking but still a little moist within (press one with a fingertip), 8 to 10 minutes. Cool on the pans on racks.