The night before you want to make the parfait, combine the oats and slivered almonds in a large mixing bowl. Add water and lemon juice, mix well. Cover and refrigerate until ready to serve.
In the morning, stir in the yogurt and maple syrup or honey (if using) and mix well.
Make the parfait by layering alternate layers of soaked oats, granola and berries in each tall glass. Top with a final layer of berries and sprinkle some chopped almonds. Serve immediately.