Peel the potatoes. Put them one by one in a large spoon and slice crosswise, but only up to the edge of the potato. This means the potatoes will still be intact on the bottom.
Put the potatoes on the baking dish and add butter. Bake the hasselback potatoes at 180°C for half an hour to start with. Turn them in the butter sauce during the baking.
Remove from the oven and top with grated cheese.
Bake the potatoes in the oven for another 15 minutes and test that they are cooked through and soft.