Preheat oven 180°C.
Lightly grease an 8” square tin with coconut oil and line with baking parchment (make sure the paper goes beyond the edges, this will help later).
In a large bowl mix together the flour, baking powder, followed by the oats, sugar, salt and cinnamon.
Then, add the coconut oil to the mix and rub in using your fingertips until the mixture resembles breadcrumbs.
Pour about two thirds of the mixture into the prepared tin, spread it out and level it by packing it down very firmly.
Bake for about 15 minutes until golden around the edges.
For the filling, mix the cornflour and lemon juice together in a large bowl to make a paste. Stir in the jam, followed by the berries.
Pour the filling over the base and spread level.
Scatter the remaining crumble mixture over the top and bake for 30 minutes, or until the crumble is golden and the filling is bubbling.
Remove from the oven and leave to cool in the tin. Once cooled, carefully lift it out using the baking parchment, cut into squares and serve.