Preheat the oven to 180 degrees Celsius (356 degrees Fahrenheit) (fan).

Cut the potatoes crosswise into slices about 0.6-0.8 cm thick. It doesn't have to be exact.

Place two wooden skewers on a cutting board. Put a potato slice between them and make many vertical cuts. The clever thing is that you can cut "completely" down without cutting through the potato, as the skewers stop you from cutting all the way through.

Turn the potato around and make many diagonal cuts.

We want the potatoes to be crispy. The easiest way to achieve this is by removing some of the starch. I usually do this by putting lukewarm water in a bowl and letting the potatoes sit in it for 1 minute. Drain the water and fill it again with lukewarm water. Repeat one more time, and finally you will see that the water you drain off is almost clear, which means you have removed almost all the starch.

Bring a pot of water with a little vinegar to a boil. Boil the potatoes for 3 minutes and drain the water. Place them on a tea towel and pat them as dry as possible on the top side.

Make the marinade: Melt butter and add oil, salt, pepper, onion powder, and a pressed/finely chopped garlic clove.

Put the potatoes individually into the bowl with the marinade and toss them around to coat well. Place the potatoes in an ovenproof dish or on a baking sheet lined with parchment paper. I did the former, but next time I will definitely use a baking sheet instead.

Bake them for 30-40 minutes until they are golden and crispy.

Take them out of the oven and place them on absorbent paper before serving.

Enjoy your meal.