Be sure that your bowl and beaters are completely clean; any trace of grease will prevent the egg whites from reaching maximum volume. These "kisses" are small; the whole recipe will probably fit on two large baking sheets. Parchment paper prevents sticking.
Adjust the oven racks to divide oven into even thirds.
Preheat oven to 250°.
Beat egg whites, cream of tartar, and salt with a mixer at high speed until foamy. Add sugar, 1 tablespoon at a time, beating until stiff peaks form. Add espresso and vanilla; beat until well-blended.
Cover 2 baking sheets with parchment paper; secure to the baking sheets with masking tape. Drop batter by level tablespoons onto prepared baking sheets. Top each mound with 1 coffee bean. Sprinkle evenly with cocoa. Bake at 250° for 2 hours or until dry. (Meringues are done when the surface is dry and meringues can be removed from paper without sticking to fingers.) Turn oven off, and partially open the oven door; leave meringues in oven 1 hour. Remove from oven; carefully remove meringues from paper. Cool completely on wire racks.
Note: Do not use egg substitute in place of egg whites.