Preheat your oven to 190C/170C fan, and line a 9x9inch square tin with parchment paper and leave to the side for now.
Whisk the flour, bicarbonate, salt, cornflour and cinnamon together so its evenly distributed, and leave to the side.
In a large bowl, melt the butter. Add in the two sugars and whisk for 2 minutes until the sugar starts to to dissolve and the mixture becomes smoother.
Add in the vanilla and egg and whisk again briefly to combine.
Add in the dry ingredients, the apple, and the chocolate chips and mix together until a thick cookie dough is formed.
Press down into the prepared tin.
Make the crumble by rubbing together the flour, butter and sugar until fine crumbs are formed, and then sprinkle over the top of the cookie dough.
Bake the cookie bars in the oven for 25-30 minutes, or until golden. The less the time, the gooier they will be.
Leave the cookie bars to cool for 10 minutes in the tin, and then finish cooling on a wire rack.
Notes
These will last in a container at room temperature for 4-5 days, if they aren't eaten already!
You can use whatever chocolate chips you like in the recipe, but I personally feel that the white chocolate works best with the flavours of the apple and cinnamon.
I found my dried apple in Tesco, and most supermarkets sell it. I've also seen it in Waitrose and some other stores.
If you can't find it, any other dried fruit will work such as apricots etc!
Using dried apple is important, as cooked apple turns mushy and wouldn't work in a cookie.
You can use pre-made crumble mix if you wish, but don't use too much otherwise it might mess up the cookie bars! No more than 125g worth.
IF you would like to use fresh apple, use baking apples (Bramley), only 150g worth in 1cm chunks, and be prepared for it to take longer to bake!