Evenly spread the date filling over the base using an offset spatula or the back of a spoon.
Sprinkle the apples over the date filling. Gently pat down to form an even layer. Squeeze the remaining dough into clumps, breaking any larger clumps apart, and scatter the clumps evenly over the apples to create the crumble topping. Place into the preheated oven and bake for 10 minutes.
Rotate pan and reduce heat to 350°F (177°C). Bake for an additional 20 to 25 minutes or until the top is a deep golden brown colour. Remove and place on a wire rack to cool completely.
Using the parchment paper overhang, lift the cooled bars from the pan to a cutting board. With a sharp serrated knife or chef’s knife, cut into 15 bars.
Store leftovers layered between parchment in an airtight container for up to 5 days or in the fridge for up to a week.