First, mix the crumble. Mash the bananas with a fork, then add the ground flaxseeds, spices and enough oat milk to have a thick, porridge-like consistency. Let it rest.
Preheat the oven to 180°C.
Peel and dice the apple, then scatter them into a baking dish. (If you like your apple crumble mushy - you can cook the apple pieces in a pan with a little water or apple juice for 5 minutes until softens. Then transfer the softened apples to the baking dish).
Dust the apple with cinnamon and ginger and scatter the chopped walnuts and dates around the apple pieces.
Drizzle with water/juice and the vanilla extract. (You don’t need water, if the apples are pre-cooked).
Top with the oat crumble evenly.
Bake in the oven for 25-30 minutes, until the crumble looks golden.
Alternatively, bake it in an Air Fryer for 20 minutes.
Let it cool a bit and serve with Greek yogurt, crème fraîche or plant-based alternatives.