Coffee and walnuts combine well with a sweet background, such as these meringues. The finely chopped chocolate adds an elusive flavor. Since there is so little of it, it adds to the flavor in general, but doesn’t overdominate.
Set racks in the upper and lower thirds of the oven and preheat to 300°F (150°C).
Place the egg whites and salt in the howl of an electric mixer and whip with the whisk attachment on medium speed until white, opaque, and beginning to hold their shape. Increase the speed to medium-high and whip in ½