Preheat the oven to 180°C.
In a large bowl, combine the oat flakes, oat flour, and cinnamon (if using), mixing well.
Make a hole in the centre and add the maple syrup and melted coconut oil.
Mix the ingredients thoroughly and set aside.
Place the berries in a baking tray.
Add 3 to 4 tbsp of oat flour to the berries.
Spread the reserved crumble mixture over the top.
Bake at 180°C for approximately 30 to 40 minutes, or until the crumble is golden brown.
Let it cool and serve with yoghurt or a scoop of ice cream, for example.