How to make
Peel the potatoes and cut them into very thin circles. Pour ice water over them and leave them in it for 30 minutes.
Then pour out the water and dry the potatoes in a cotton towel.
In a bowl, mix the cocoa and powdered sugar.
Roll each potato slice in this mixture.
Grease a Teflon baking pan with butter and arrange the potato slices in it.
Bake them in a preheated oven at 390°F (200 degrees) with the fan on for about 25 minutes until you have crispy baked potatoes.