Wash the potatoes well under running water and pat dry.
Locate the flattest side of your potato and stick a skewer through it at about 0.5 cm. from the bottom and then cut wafer-thin notches in the thickest side of the potato with a sharp knife up to the skewer.
Carefully remove the skewers and place the potatoes on a plate in the microwave. Precook the potatoes for about 3 minutes on the highest setting. You will see that the potatoes steams well afterwards.
Place the Hasselback potatoes in the skillet and cover with the melted fat. Let the potatoes cook (+-1h) until you notice that the slices fall open and start looking crispy. Pour the melted fat from the skillet over the potatoes with a spoon every 10 minutes.