Whisk the egg whites and sugar together in a metallic container. Place this metallic container on a double boiler with hot simmering water, while whisking the egg mixture for couple of minutes.
Stir the egg mix till the sugar is dissolved. Remove it from heat , add the vanilla and whisk it till soft peaks are formed.
Add salt and whisk again to form hard peaks. The whole procedure takes about 6-7 minutes. Fold in the cocoa powder into the meringue mix.
Whisk the egg whites and sugar together in a metallic container.
Pipe the mix on a tray with butter paper on it, bake at 100℃ , in a preheated oven for 1 hour. Cool it completely, preferably overnight and serve.