Preheat oven to 200 degrees F (95 degrees C). Line a baking sheet with parchment paper. Line a large plate with waxed paper.
Beat egg whites, coffee granules, vanilla extract, cream of tartar, and salt with an electric mixer at high speed until soft peaks form, 3 to 5 minutes. Add sugar, 1 tablespoon at a time, beating constantly, until stiff but still glossy peaks form, 3 to 5 minutes.
Drop egg white mixture by rounded tablespoons 2 inches apart on prepared baking sheet (alternately, fill a pastry bag fitted with a star tip with egg white mixture and pipe out 1- to 1 1/2-inch stars).
Bake in the preheated oven until kisses are firm and dry, about 2 hours. Cool on the baking sheet set on a wire rack for 1 hour.
Melt chocolate in the top of a double boiler over simmering water, stirring frequently and scraping down the sides with a rubber spatula to avoid scorching. Remove from heat and cool slightly.
Peel kisses from parchment paper. Dip the base of each kiss in melted chocolate and transfer to waxed paper-lined plate. Freeze kisses until chocolate hardens, 2 to 3 minutes.
Kisses can be made 1 week ahead and kept in an airtight container at room temperature. They can also be frozen, tightly wrapped in plastic wrap and put in a zip-top plastic bag, for up to 1 month; thaw still wrapped.
Per Serving: 26 calories;1 g fat;
3.9 g carbohydrates;
0.4 g protein;
< 1 mg cholesterol;
5 mg sodium.