Preheat oven to 200 degrees F (105 degrees C) and place the rack in the center of your oven. Line a baking sheet with parchment paper. You can form the cookies with a pastry bag fitted with a 1/2 inch (1.25 cm) plain tip, or just use two spoons.
In the bowl of your electric mixer, with the whisk attachment, beat the egg whites on low-medium speed until foamy. Add the cream of tartar and continue to beat the whites until they hold soft peaks. Add the sugar, a little at a time, and continue to beat until the meringue holds very stiff peaks. Gently fold in cacao nibs.
Note: The meringue is done when it holds stiff peaks and when you rub a little between your thumb and index finger it does not feel gritty. If it feels gritty the sugar has not fully dissolved so keep beating until it feels smooth between your fingers.
Before placing the cookies on the cookie sheet, place a little of the meringue on the underside of each corner of the parchment paper. This will prevent the paper from sliding. Transfer the meringue to a pastry bag fitted with a 1/2 inch (1.25 cm) tip. Pipe 2 1/2 inch (6 cm) rounds of meringue in rows on the prepared baking sheet. Alternatively, spoon mounds of meringue, using two spoons, onto the prepared sheets. Sprinkle with a few shaved almonds, if desired.
Bake the meringues for approximately 1 1/2 to 1 3/4 hours, rotating the baking sheet from front to back (about half way through) to ensure even baking. The meringues are done when they are pale in color and fairly crisp. Turn off the oven, open the door a crack, and leave the meringues in the oven to finish drying overnight.