In a small bowl, mix the plant milk with the chia seeds and leave to rest for about 10 minutes, allowing it to thicken slightly.
In a blender, combine the mashed banana, cinnamon, cottage cheese, date syrup and oats. Blend until you have a thick batter.
Add the chia milk mixture and blend again until smooth. The mixture should be thick but not solid—if needed, add a little more milk to adjust the consistency.
Fold in the chopped walnuts.
Transfer the mixture into two small or one larger silicone mould or ovenproof dish.
Bake in a preheated oven at 180°C for about 20 minutes, until set and lightly golden.
Alternatively, cook in an air fryer using the baking setting for around 15 minutes.
Allow to cool slightly before slicing.
Serve warm or at room temperature, on its own or with Greek yogurt and an extra drizzle of date syrup.