Preheat oven to 400F conventional or 375F convection.
Peel potatoes and place in a pot or bowl with cool water.
In a large bowl, mix the cream, salt, shallot and rosemary.
Slice the potatoes 1/8 inch thick with mandoline or knife and place in the bowl with the cream mixture.
Toss the potatoes with the cream and then place in a 13x9 baking dish. be sure that the sliced are evenly distributed throughout the dish.
Cover the dish with foil. Roate the dish after 30 minutes and using a paring knife or skewer test the potatoes after an hour. The dish is done when they are soft when pierced.