Toss the apples and sugar together in a bowl. Melt the butter over a low heat in a frying pan, add the apples and cook gently for 5 minutes, turning occasionally, until softened.
Increase the heat to high and cook for a further 2 minutes until the apples are starting to caramelize. Add the Calvados and carefully flambé, swirling the pan gently until the flames have gone.
Divide the apples between 2 bowls and pour over the juices from the pan. Top each portion with a spoonful of crème fraîche and a pinch of cinnamon and serve immediately.