Mix chopped strawberries, raspberries and blueberries and add the sprinkle of sweetener. Let sit to macerate while you prepare the other layers.
Prepare pudding mix according to package directions, reducing milk by ½ cup.
Fold half of the Cool Whip into the pudding.
In a pretty, clear bowl, make the layers (make sure to spread it all to the edges of the bowl for presentation purposes):
Layer as follows: ⅓ cake, ½ fruit, ½ pudding, ⅓ cake, ½ fruit, ½ pudding, ⅓ cake.
Top with remaining Cool Whip and berry garnish.
Refrigerate until ready for serving.
