Unroll the dough and place it on a baking tray together with the baking paper. If necessary, form the corners slightly oval.
Coarsely grate the cheese. Wash the marjoram, shake dry. Pluck off leaves, chop. Stir both into the sour cream. Season with pepper and a little salt. Spread the sour cream on the tarte flambée, leaving a small rim all around.
Clean and wash the leek and cut into fine rings. Sprinkle evenly over the leek. Bake the tarte flambée in a preheated oven (electric cooker: 225 °C/circulating air: 200 °C/gas: see manufacturer) for 12-15 minutes. Pluck the ham into pieces and spread on the tarte flambée.
Serve the cake immediately. Drink tip: fresh white wine, e.g. a Rivaner.