This article is worth reading as it includes several ideas for the
classic apple tart (note that cinnamon is not mentioned - thankfully).

https://www.theguardian.com/food/201...le-tart-recipe

http://tiny.cc/m5gvyy

I have made the version with a tart apple purée as the base layer - made
with Granny Smiths to which I added a generous dollop of softened butter
when puréeing in the blender.
I've also made a version where I have generously sprinkled
icing/confectioner's sugar over the cooked tart followed by caramelising
under the grill or with a blow torch.
Either way, the butter in the purée makes a noticeable difference and is
absolutely delicious.