Preheat oven to 275F and line baking sheet with parchment paper.
In a large bowl, with whisk or mixer with whisk attachment, add the Egg Whites and start to whisk until stiff peaks start to form, 5 - 10 minutes.
Gradually add in Sugar, a little at a time until well incorporated.
Continue to whisk and slowly add in the sifted Cocoa Powder, keep whisking until well blended and peaks are stiff and you know it's ready when you rub a little of the Meringue batter between your fingers and it's smooth and not grainy from the sugar, if grainy - then continue to whisk just a minute or two longer and it should be ready.
With a rubber spatula, gently fold in the chopped Chocolate and if using toasted nuts, add them now as well.
On parchment lined baking sheet, generously spoon a heaping tablespoon of Meringue about 2 inches apart.
Bake the Meringues for about 40 minutes or until the Meringues can easily be removed from parchment paper.
Once Meringues are baked, turn off the oven and allow the Meringues to cool in the oven for at least an hour. This step prevents the Meringues from cracking.