Good, easy potato dishes are something I always like to have in my back pocket, especially in the winter when something cozy and belly-warming is in order. I haven’t yet tired of smashing potatoes, and I’m not sure I ever will.The idea for this dish came to me in a dream: What if I just smashed whole roasted potatoes, right in the baking dish, and then poured roasted garlic–laced cream over them, and then baked them with a scattering of Parmesan until they were crispy and golden and delicious? The use of cream here is judicious, and most of it is absorbed by the potatoes, resulting in an unctuous but not overly rich gratin. The shallots end up caramelized and sticky, and you’ll find yourself digging for them.I like to use an enameled cast-iron baking dish for a million different things, from fruit crisps to roasting a chicken to baking a bread pudding, and it’s the perfect vessel to use here. Failing that, a ceramic baking dish works, too, as would a large cast-iron skillet. All the potatoes should fit easily in one layer (leaving a little room for the shallots). Try out different baking dishes before you oil the potatoes (just tumble them in and see if they fit in a single layer) to find the right one. After roasting until just tender, use a potato masher (or the bottom of a sturdy mug) to flatten each one.Sometimes, I like to prep, or mise, all of my ingredients before I start cooking, but that’s not always the most efficient way. Here, each step is quick to prepare and can be done as you proceed with the recipe. There is a little in and out of the oven with this recipe, but it’s seamless and simple and will have your tablemates swooning over the divine combination of basic ingredients that come together in a way that is much, much more than the sum of its parts.If you want to make this a few hours ahead of time, go as far as smashing the potatoes (leave at room temperature) and making the cream mixture. About a half hour before you want to serve, pour the cream over and bake for 30 to 35 minutes. Go with something simple like a roast or steaks and a crisp green salad with this luxurious side dish.