These heavenly cookies will have everyone applauding. Their light, barely-there texture, deep chocolate flavor and orange fragrance make for a show-stopper. If you're not eating them immediately, allow the cookies to cool completely, then store in an airtight container in a cool, dry place until ready to serve.
Makes 2 dozen
Preheat oven to 275°F. Line two large baking sheets with parchment paper; set aside. Pour enough water into a medium pot to reach a depth of about 2 inches; bring to a simmer. Whisk egg whites, sugar, salt and orange zest together in a heatproof bowl that easily sits on top of the pot. Arrange bowl over simmering water and cook, whisking constantly, until mixture is hot throughout and begins to thicken, about 5 minutes. (If mixture seems to be getting hot too quickly, check the water to make sure it's not boiling. Briefly remove the bowl from the pot to let the contents cool slightly before continuing, if needed.) Transfer hot egg mixture to a large bowl and beat with an electric mixer (fit with a whisk attachment) on medium-high speed until stiff peaks form, 8 to 10 minutes. Gradually add melted chocolate, folding the mixture together just until the chocolate is swirled in. Using a large spoon, drop about 1/3 cup of the batter onto the prepared baking sheets to form each cookie, making sure to space them about 2 inches apart. Swirl the top of each cookie with the back of a small spoon to form a peak, if you like. Bake until dried out but still a bit chewy on the inside, about 40 minutes. Set aside to let cool, then serve.