Parfaits can be made up to 2 days in advance. You can mix all the ingredients in a blender and freeze them into popsicles too!
In medium bowl whisk together the first four ingredients until they're well combined. Spoon 2 tablespoons of yogurt mixture into the bottom of four clear glasses. Top with some raspberries/blueberries and repeat until all of the yogurt and berries are used up. Sprinkle with walnuts; refrigerate until ready to serve. Each serving is 1 block.