Receta Old-Fashioned Potato Gratin

This is a traditional, old-fashioned potato gratin my great-grandmother, Mamma, might have made. She was a fantastic baker and cook, and her dinners and brunches were legendary. But this is a dish that invites your own stamp, so feel free to riff away. What we call potato gratin today originated in the Dauphiné region of France as gratin dauphinois, and has as many variations as there are cooks who make it. The original recipe, going back to the late 1700’s, calls for thinly sliced raw potatoes layered in a shallow dish rubbed with butter and garlic, and covered with cream or crème fraîche. Common variations include a melty cheese like Gruyère, eggs, and a mixture of milk and cream. For mine, I included the Gruyère, used a mixture of milk,…