Slice off both ends of the potatoes. Punch a 5 cm. diameter steel tube or pastry cutter through the potatoes to produce long cylinders from the centre of all three. Slice on a mandolin into 3 mm. thick discs. Place on a clean kitchen cloth and pat dry. Lightly season the potatoes with salt and freshly ground pepper.
Melt 30 ml. clarified butter in each of four blini pans. Remove the pans from the heat and arrange 36 overlapping slices of potato into each pan to fit tightly. Cook the potato gallettes over a medium heat for 5–6 minutes until crisp and golden. Flip over with a palette knife and cook the other side. Lift the potato gallettes out of the pans and drain on kitchen paper. Lightly season with salt and freshly ground pepper. The potato gallettes can be prepared in advance and reheated in the oven in a little clarified butter before serving.