I have a recipe for a potato gratin in my last cookbook "Dinner Solved!" that I firmly stand by. Here is another that I firmly stand by. And I plan to come up with more such recipes to firmly stand by because I am committed to reminding all of us why gratins are one of the best things that could ever happen to a potato, ever.
This is a rich gratin, made with all cream, no milk or even half and half. I'm not apologizing, just explaining. In general, I like my indulgent dishes flat-out indulgent, and my healthier food in the form of broiled fish, or salads. And I don't have a problem with the two sharing a plate. This gratin, for instance, would be lovely next to a piece of roasted salmon with a peppery green salad alongside them.
If you have a mandolin and the inclination to use it, please do, and you will get lovely, paper-thin slices for a sultry and elegantly stratified gratin. If not, use the slicing blade in your food processor or a sharp knife; the slices will likely not be as thin, but that's A-OK.