This recipe for buttermilk–blue cheese potato au gratin combines the rich flavors of blue cheese, mustard, and Worcestershire sauce.
By Amy Traverso
Nov 05 2021
Buttermilk–Blue Cheese Potato au GratinPhoto Credit : Heath Robbins
Mary Lou Carlson of Bothell, Washington, was one of 17 winners of our October 1988 “Great New England Cook-Off” for her fresh take on potato casserole. Like many “gourmet” recipes of the era, this buttermilk–blue cheese potato au gratin had a laundry list of ingredients, so we cut it back while preserving the rich flavors of the blue cheese, mustard, and Worcestershire sauce.
6 large Yukon Gold potatoes, peeled sliced ¼-inch-thick
3 tablespoons salted butter, plus more for the pan
3 shallots, minced
2 ½ tablespoons all-purpose flour
1 ½ cups whole or 2% milk
1 cup buttermilk
2 ½ ounces blue cheese, crumbled, divided
2 teaspoons mustard (Dijon or brown)
2 teaspoons Worcestershire sauce
1 ½ teaspoons table salt
½ teaspoon freshly ground black pepper
¾ cup grated Parmesan cheese, divided
Preheat the oven to 350°. Lightly grease a 9- by 13-inch baking dish. Arrange half of the potato slices in 3 overlapping rows in the bottom of the prepared dish and set aside.
In a medium saucepan over low heat, melt the butter. Add shallots and cook, stirring, for 1 minute. Add the flour, stir or whisk to blend, and cook for 3 minutes. Add the milk and buttermilk. Cook, stirring constantly, until the sauce thickens and bubbles. Remove the saucepan from the heat. Add the blue cheese, mustard, Worcestershire sauce, salt, and pepper; stir to incorporate.
Spread half of the sauce over the potatoes, then sprinkle with half the Parmesan cheese. Layer the remaining potatoes over the cheese and cover with the remaining sauce. Sprinkle with the remaining Parmesan.
Bake until the potatoes are tender and the cheese on top is golden brown, 65 to 75 minutes (you can run the dish briefly under a broiler for extra browning, if you like).