Before you start cooking: Pre-heat oven to 370 °F (190 °C), ideally fan-forced. Line a baking tray with parchment paper.
Peel the potatoes and cut them into wedges: slice a potato in half lengthwise, repeat, and cut each half in half again. You’ll get 4 wedges out of 1 mid-sized potato.
Place the wedges on a lined baking tray and bake to golden brown perfection. It takes about 45 minutes. The wedges will be crispy on the surface and very soft inside.
Get a clean kitchen towel in your hand, take each potato wedge and smash it. It’s enough if you press the potato gently; the crispy crust cracks, and the pillowy inside appears. Be careful, the potato wedges are still hot.
Put the smashed potatoes in a bowl. Once all wedges are crushed, place over them a few butter slices. Cover the bowl with a towel and let the butter melt into smashed potato wedges.
Salt to your liking, stir and serve.