Preheat oven until 350 degrees F. In a mixer bowl combine crust ingredients. Mix until well combined. Press crust on the bottom of a 10 inch tart pan. Bake for 10 minutes. Combine the middle layer ingredients together. Carefully pour over the baked crust. Return the torte to the oven. Bake an additional 20-25 minutes or until rhubarb filling is set. While filling is baking, whip egg whites until semi-stiff. Add sweetener and salt. Mix again. Spread beaten egg whites over baked filling. Return to oven and bake for 10-12 minutes or until egg whites is browned. Cool. Serves 10.