Prepare two flax eggs by mixing the flaxmeal with the water. Let sit for 8 minutes.
Preheat the oven to 180°C.
In a medium bowl mix the oats, oat flour, maca (optional), cinnamon, baking powder and salt. Add the plant milk, maple syrup, oil and vanilla and mix again. Let sit for 15 minutes.
Meanwhile, prepare the crumble by mixing all its ingredients until a homogeneous consistency is obtained. Reserve.
Pour the oat mix into a baking dish (you can use an 8 ”or even slightly larger one) and cover it with the crumble mix (grab small pieces of the crumble mix and distribute them all over the top).
Bake for 40 minutes or until you insert a knife in the center and it comes out clean.