If you love mug cakes (of course you do!) then you will love this quick dessert of buttery flaky pastry  topped with a caramel fudgy frangipane and paper thin apple slices, baked to golden must-be-eaten-with-a-dollop-of-ice cream perfection. An abomination of a traditional tart masquerading as a thin-crust sweet pizza, who really cares what it is