It's fun to use pistachios for some of these and pecans for others, but of course you can stick with one or the other. It's best to bake them on a dry day; if it's even slightly humid, the meringues may take longer to crisp in the oven. The meringues can be made up to five days ahead and stored in a cool, dry place.
- 3 large egg whites
- 3/4 cup sugar
- 1/8 teaspoon coarse salt
- 1/8 teaspoon cream of tartar
- 1 1/2 teaspoons Trablit coffee extract (available at culinarydistrict.com) or 1 tablespoon pure vanilla extract
- 6 ounces bittersweet chocolate, chopped
- 1 3/4 cups pistachios or 1 1/2 cups pecans, toasted and finely chopped
Preheat oven to 200 degrees. Combine egg whites and sugar in a bowl set over a saucepan of simmering water, and whisk until sugar is dissolved and mixture is warm, about 3 minutes. Whisk in salt and cream of tartar; remove from heat.
Beat mixture with an electric mixer on medium-high speed until stiff, glossy peaks form and meringue is mostly cooled, about 7 minutes. Beat in extract.
Fit a pastry bag with a 3/8-inch round tip (Ateco #804) and fill bag with meringue. Pipe meringue "kisses," each 1 inch in diameter, releasing pressure and pulling pastry bag straight up to create each, 1 inch apart on parchment-lined baking sheets. Bake until crisp on outside and able to release easily from parchment, about 1 hour, 15 minutes. Transfer to a wire rack and let cool completely.
Melt chocolate in a bowl set over a saucepan of simmering water, stirring until smooth; remove from heat. Working 1 at a time, dip base of each meringue in chocolate, then coat base completely with nuts. Transfer to parchment-lined baking sheets and let stand until set, about 1 hour. Meringues can be made 5 days ahead and stored in a cool, dry place at room temperature.