- 2 tablepoons unsalted butter
- 2 tablepoons all-purpose flour
- 1 cup whole milk
- 1 1/2 tablepoons whole-grain mustard
- Kosher salt
- 1 pound fingerling potatoes, scrubbed but not peeled, then sliced 1/8 inch thick (4 cups)
- 3/4 cup heavy cream
- 1 teaspoon chopped rosemary
- 1/4 pound raclette cheese, coarsely shredded (1 cup)
- 12 cornichons, sliced
How to make this recipe
- In a medium saucepan, melt the butter. Add the flour and cook over moderately low heat, whisking, until light golden, about 3 minutes. Whisk in the milk and bring to a simmer, whisking frequently. Cook, whisking, until the sauce is thick enough to coat the back of a spoon, about 5 minutes. Scrape the béchamel into a medium bowl, whisk in the mustard and season with salt. Let cool completely.
- Preheat the oven to 350°. In an 8-by-11-inch baking dish, toss the potatoes with the cream, rosemary, 2 teaspoons of salt and 1/4 teaspoon of pepper; mix well. Cover and bake until the potatoes are tender when pierced, about 30 minutes. Uncover and bake until the cream reduces and thickens, about 15 minutes.
- Spoon the béchamel over the potatoes and bake for about 10 minutes, until golden and bubbly. Scatter the raclette cheese on top and bake for 5 minutes longer, until melted. Let stand for 10 minutes, then top with the cornichons and serve hot.