Cut the bread so that the two slices are still attached at the bottom, like a man’s wallet.
Mix the crème fraîche and mustard together with paprika, and spread it generously on both insides of the "wallet". Season with pepper.
Make a sandwich within a sandwich: scatter in a layer of grated cheese, lay the ham on top of it, and scatter more grated cheese on top of the ham. (Alternatively, stir the cheese into the cream and mustard mixture, spread on both sides of the bread with the ham in the middle.)
Press the sandwich together with your hand. Fry in clarified butter in a frying pan, a few minutes per side until it’s golden on the outside, and melting in the middle. Serve hot with a bit of salad.