In a large bowl - combine the oats, flour, protein powder, cinnamon, and baking powder. Pour in the maple syrup and milk, then mix everything together directly in the dish until well combined. Stir through the apple slices.
Pour into a large baking dish approx. 20 × 28 cm. Sprinkle the flaked almonds evenly over the top.
Bake for 35-40 minutes, or until the top is golden and the oats are set.
Allow to cool slightly before slicing into portions.
