In a stand mixer fitted with whisk attachment, whip the egg whites on medium speed until soft peaks form. Add the confectioners' sugar and cream of tartar. Slow down the mixer and continue until stiff peaks form. Scoop meringues and place on a baking sheet fitted with a nonstick pad. Bake for 2 1/2 hours. When done, remove from the oven and let cool.
Meanwhile, combine the dark chocolate, heavy cream and 2 tablespoons of the granulated sugar in a saucepan and cook over low heat until melted. Stir to make sure the ingredients mix together. Pour over a baking sheet fitted with a nonstick pad and let cool.
In a saucepan or skillet, cook the berries with the remaining 2 tablespoons granulated sugar until they becomes syrupy and thickened.
Hollow out a space at the bottom of your meringue; save the hollowed out portion. Spoon the chocolate mixture into the meringue hole. Cover back up with the piece of meringue you removed. Plate the meringues. Drizzle the blueberry and raspberry reduction over top of your meringues liberally.
This recipe was created by a contestant during a cooking competition. It has not been tested for home use.