Healthy Apple Crumble

"This recipe requires that you prepare the base, filling and the crumble separately, but you don’t need any special cooking skills to make it. The pan that I’ve used for this recipe measures 13×19 cm (5×7 inches), but if you have one that is a little bigger, it will also be fine. The only change would be that each layer is thinner and, as a result, you would get apple crumble bars that you could eat simply with the help of two fingers, exactly like in Danielle’s recipe."