Begin by pre-heating your oven to 190 degrees Celsius. Then start making the shortbread dough, but doubling or even trebling the amounts. Once you have the dough ready, set aside.
Get a tart baking tin ready by shaving small bits of the butter and spreading this over the inside of the tin leaving an inch edge gap to the wall of the tin all round. Add the thyme leaves and then start on your apples. Peel and core them before slicing the apples then adding the slices to a bowl. Pour over the sugar and cinnamon then use a spoon to mix everything so the apples are well coated. Once done, lay the slices in the tin over the butter shavings and pour any remaining sugar over the top.
Having prepared the tine with the apples, take a sheet of baking paper and place this on a work surface. Place the shortbread dough as a ball in the centre of the paper and then place another sheet of baking paper on top. Now use a rolling pin to spread out the dough into a circle big enough to cover the apples. Remove the top sheet of baking paper and use the bottom to manoeuvre the dough circle over the prepared apples. Flip on top and tuck the sides down over the apples, then use a fork to prick holes all over the shortbread dough. Place in the oven for 30 – 40 minutes, if the top looks to be getting too dark remove from the oven. Once cooked, allow to cool for wat least 15 minutes as the cooked dough will need to harden (even better if you can leave it for 30 to 40 minutes). Serve by using a cake slice to cut a portion, lift it out then place the plate on top (upside down) then flip.