Remember that potatoes have starch which acts as a thickener. Scallop potatoes do not require a condensed type soup, unless watered down somewhat. Next batch I will follow "Diana" in her old-fashioned recipe, Pirex type dish in the conventional oven, but with either home made chicken stock and butter, or milk and butter. Only white soup, if that's what you wish to use, should be used as the whiteness of the potato should be respected and retained. The aim is to allow the slow cooker to leach out the potato starch which is the thickener. Thick soup already has thickener in it and doesn't appeal to me, anyway. No further thickener is required from the white potato slices.
