Beat the egg whites with the hand mixer until stiff. Slowly add sugar and keep beating until it has dissolved. Sift in the powdered sugar, espresso and cocoa powder and fold in until everything is smooth.
Use the piping bag (middle spout) to squirt the meringue into hazelnut-sized dots onto the baking sheet (baking paper) and allow to dry at approx. 80 degrees (convection 60) for about 1.5 hours.
When the meringues are cold, melt the couverture and drizzle over the meringues.