Preheat the oven to 180 degrees Celsius (350 degrees Fahrenheit)
For the apples:
Place the apples, coconut oil, coconut sugar, vanilla, cinnamon and salt in a pan with a lid
Leave to cook on a low heat, stirring occasionally, for about 20 minutes until softened
Dissolve the cornflour in a tiny splash of water in a small bowl
Once the apples have cooked, add the cornflour and water mixture and mix well
Once the apples have thickened (takes about 30 seconds), turn off the heat
For the base and topping:
Place all ingredients in a food processor and whizz until you get a fairly smooth and firm dough
To assemble:
Divide the dough for the base and topping into thirds
Take two thirds and place into a square or rectangular baking tin lined with greased baking paper (I used a 23cm/9inch square baking tin)
Spread it carefully across the bottom of the tin, using the bottom of a glass to even out the surface, if necessary
Bake in oven for 15 minutes until firm to the touch
Spread the cooked apple mixture over the base
Use your fingers to crumble the rest of the dough over the top until it is all used up and the apples are roughly covered
Bake in the oven for 15 minutes, or until golden brown and crispy on top
Leave to cool before cutting into squares
Keeps covered in the fridge for up to a few days
Notes
You can top it with any type of chopped nuts before baking: pecan nuts, walnuts, pistachios, desiccated coconut, flaked coconut etc.
For an oil-free option, omit the coconut oil from the apples and substitute the coconut oil in the crumble topping with nut butter such as almond butter or peanut butter.