Set the oven to 225°C (435°F). Melt the butter in a saucepan and set it to the side.
Peel the potatoes. Place each potato in a deep wooden spoon and cut until the knife hits the spoon’s edges. If you don’t have a spoon, simply cut the potato freely but make sure not to cut it all the way through.
Take out an oven-proof dish. Brush the dish with a little of the butter. Place the potatoes in the dish and brush them with more of the butter. Sprinkle the potatoes with sea salt.
Cook your Hasselback potatoes in the oven for about 30 minutes. Take them out, brush with any remaining butter, and sprinkle them with breadcrumbs.
Cook for another 10-15 minutes (depending on size) until they become golden and are getting softer when you prick them with a toothpick. If the potatoes still are a bit hard but get a lot of color, cover them with foil until they are cooked through.
Enjoy your Hasselback potatoes! They make any meal a bit more festive.