Place the banana, half the berries and 1 tbsp of maple syrup in a 15x25cm dish. Bake at 375F for 10 to 12 minutes.
Meanwhile, combine the oats, almonds, baking powder and cinnamon. In another bowl, combine the milk, egg, vanilla and 1 tbsp of maple syrup.
When the banana mix is ready, spread the oat mixture over the bananas. Then pour the milk mixture over the oats evenly. Sprinkle with remaining berries (1/4 cup).
Bake for 20 to 25 minutes or until oats are golden brown. Serve hot with Greek yogurt.