Mix flour with icing sugar then add butter and rub with fingertips ( or using a food processor) until you have crumbles.Beat egg with lemon and water, add it to the pastry and knead until you have a smooth ball.Wrap in cling film then let it rest in fridge at least 15 minutes.
Heat oven at 200°C and put into a baking tray.Take a cake tin of 25 cm diameter about 3 cm deep.
Roll out the dough in a thin layer and line the cake tin with the pastry.
For the frangipane cream:
Beat butter and sugar until fluffy, add flour, almond flour and almond extract, mix well and spread over the pastry.
For the apple cover:
Peel, core and thinly slice apples, from edges to centre cover the cake with slices, add the butter here and there.Put in the oven over the heated baking tray and bake for 15 minutes, then sprinkle sugar on top and bake for mere 10- 15 minutes.
Let the tart cool completely and serve with ice cream or whipped cream or clotted cream.