Potato Roll with Borage

Boil the potatoes for 15 minutes in a pressure cooker. In the meantime, blanch the borage leaves, drain and spread on a dish towel. Peel and mash the potatoes. Add the egg, half the butter and half the grated Grana Padano cheese, salt, pepper and nutmeg. Arrange the borage leaves on a sheet of parchment paper, forming a rectangle 11 3/4 x 7 3/4 inches; cover with the slices of ham and, finally, with the potatoes. Roll into a log, keeping it tight in the paper. Set it aside to rest, then remove the paper and slice. Arrange in a baking dish, sprinkle with grated Grana Padano cheese and butter and brown in the oven for 10 minutes.