Using a plate as a template cut out 8 inch or 5 inch circles. Move straight onto a baking sheet lined with greased baking paper, and leave in the fridge to chill and rest.
Meanwhile, melt the butter in a large pan and add the Bramley apples, 55g caster sugar and a splash of water. Turn onto a low heat and cook for 10 minutes. Mix with a metal spoon to a puree. Cool slightly and spread onto the pastry bases, leaving a 1cm strip around the edge of the pastry.
Cover neatly with the Granny Smith apple slices, then cook in the oven for 20 to 25 minutes.
Sprinkle with tablespoon of caster sugar and, using a blow torch or placing under a hot grill, caramelise the top for a few seconds.
Move the tart onto the serving plate. Pour over the Calvados and set light to the liquid.