Divide the water, 1/2 cup water into 2 small bowls. Sprinkle 2 tablespoons and 1 teaspoon unflavored gelatin in each bowl. Allow to soften for 5 minutes. Cherry Layer: Heat one bowl of softened gelatin until clear. I do it for 45 seconds in the microwave. Whisk in Cherry Kool Aid, Cherry Extract, and Gentle Sweet. Stir until Gentle Sweet is dissolved. Add water and salt. Whisk well. Lightly spray a 10x15 pan with Pam Spray. Pour jello into a greased 10 x 15 baking pan . Refrigerate. White Layer: Heat remaining softened gelatin until syrupy and clear. Whisk in vanilla, Gentle Sweet, yogurt, and water. When cherry layer is set, pour white layer carefully over it, spreading with a spoon. Refrigerate until set but still slightly tacky. Starting at the wide end roll jelly into a jelly roll. Refrigerate for 1 hour until totally firm. Cut with a sharp knife. 18 slices.