2 egg whites, at room temperature
1/4 teaspoon cream of tartar
1/2 cup sugar substitute
2 tablespoons unsweetened cocoa powder, lumps removed
1/2 teaspoon vanilla extract
Preheat oven to 250°F. Place egg whites and cream of tartar in a clean bowl or electric mixer fitted with whisk attachment. Whisk at highest speed until whites form soft peaks that hold their shape when you lift the whisk. Add the sugar substitute, 1 tablespoon at a time; whisk until whites turn glossy and form stiff peaks that hold their shape. Do not underbeat. Whisk in cocoa and vanilla until blended.
Line a baking sheet with parchment paper. Fit a large star nozzle into a pastry bag. Fill pastry bag with meringue. Pipe 20 meringue kisses onto prepared sheet. Bake 30 mintues, until crisp and dry. Turn oven off, let cookies cool in oven for 30 minutes. Remove from baking sheet.