Peel, wash and roughly grate the potatoes and pour so much cold water over them that the potatoes are covered. Let stand for about 30 minutes.
Melt the butter. Drain the potatoes, let them drip off and squeeze lightly in a tea towel.
Mix potatoes, butter and cheese. Season with salt and pepper. Spread the mixture thinly on a baking tray lined with baking paper. Bake in a hot oven (electric cooker: 200 °C/circulating air: 180 °C/gas: see manufacturer) for about 30 minutes.