Preheat Oven to 275°F / 135°F. 

• Line a large baking sheet with parchment paper.
• In the bowl of your mixer, beat the egg whites until the yellowing color turn white, add sugar, salt and cream of tartar and beat until the eggs are glossy and to a firm pic.
• Using a pastry bag fitted with a 3/8" round tip.  Pipe 12 stem and 12 caps like the chef did in the video.
• Bake for about 45 minutes until they are dry and let them cool on paper completely to room temp. 
• Dust the tops and stems lightly with cocoa powder. 
• Transfer them to an airtight container at room temp, not in the refrigerate.