Peel the apple, cut out the core and cut into thin slices. Brush the dough with crème fraîche, cover with the apple slices and sprinkle with sugar. Bake in the oven, preheated to 250 degrees, on the lower rack until the dough bubbles and starts to brown slightly at the edge.
Take out the tarte flambée, sprinkle with cinnamon and sprinkle with calvados.