Preheat the oven to 160-180˚C.
In a saucepan, over medium heat, melt 25g of butter and add the apples and pear pieces. Add the cinnamon and the brown sugar. Cook for 5 minutes until the apple are starting to soften. Remove from the heat and set aside to cool for a few minutes.
Meanwhile, prepare the crumble topping.
Sift the flour into a bowl and add the caster sugar, 60g of butter, flaked almonds, porridge, and baking powder. Combine until the mixture resembles breadcrumbs.
Unroll the puff pastry and place on a parchment lined baking tray.
Spoon the apple mixture on the pastry and scatter the crumble mixture over. Gently press to ensure the crumble is settle on the apple mixture.
Carefully place in the oven and bake for 30-35 minutes or until golden brown and cooked through.
Remove from the oven and serve warm with some cream or at room temperature with a warm cup of tea of coffee.