Preheat oven to 180°C (350°F) and line a baking pan with parchment paper.
In a bowl, mix oats, flour, brown sugar, cinnamon, baking powder, and salt.
Pour in melted coconut oil and stir until crumbly and well mixed.
Press two-thirds of the mixture into the pan to form the base.
Bake for 10 minutes and set aside.
In a saucepan, cook apples, coconut sugar, cornstarch, lemon juice, cinnamon, and water for 8–10 minutes until thick and glossy.
Spread the apple mixture evenly over the baked crust.
Sprinkle the remaining crumble mixture on top.
Bake again for 25 minutes until golden and crisp.
Cool completely before slicing into bars — patience, darling, is rewarded.
