This new take on the traditional potato au gratin mixes things up by adding celeriac and apples to the creamy potato dish. Celeriac is the root of the celery plant and has a distinctive celery flavor with a carrotlike texture. It is important to make sure the slices of potato and celeriac are cut to the same thickness to ensure even cooking. A mandoline is the easiest way to get uniformly thin slices. Start to finish: 2 hours (1 hour active). Servings: 10.
Ingredients
4 tablespoons ( 1/2 stick) butter
1/4 cup all-purpose flour
4 cups whole milk
4 teaspoons Dijon-style mustard
2 cups shredded Monterey Jack cheese, divided
2 cups shredded sharp cheddar cheese, divided
Salt and ground white pepper, to taste
2 large russet potatoes, peeled and thinly sliced
1 large celeriac root, peeled, quartered and thinly sliced
3 green apples, peeled, cored and thinly sliced
Directions
In a large saucepan over medium heat, melt the butter. Stir in the flour and cook for 2 minutes. A little at a time, whisk in the milk. Bring the mixture to a boil, then reduce to a simmer and cook for 5 minutes. Remove the pan from the heat and whisk in the mustard.
Stir in 1 1/2 cups of the Monterey Jack cheese and 1 1/2 cups of the cheddar cheese, stirring until melted. Season the sauce with salt and white pepper.
Fill a second large saucepan with the potatoes, then add enough water to cover. Bring to a boil and cook for 5 minutes. Use a slotted spoon to remove the potatoes from the water and transfer to a plate. Add the celeriac slices to the water and cook for 5 minutes. Use a slotted spoon to remove the celeriac from the water and transfer to a plate.
Heat the oven to 350 degrees.
In a large casserole dish, arrange an even layer of potato slices over the bottom. Top the potatoes with several spoons of cheese sauce. Add a layer of celeriac, followed by a few spoons of cheese sauce. Finally add a layer of apples, followed by a bit more cheese sauce.
Continue layering until all the ingredients are used, ending with a final layer of cheese sauce. Top with remaining Monterey Jack and cheddar cheeses. Bake for 30 to 40 minutes, or until the potatoes and celeriac are tender and cooked through when pierced with a knife. If the cheese on top begins to brown too much, cover the casserole with foil.
Let stand at room temperature for 10 minutes before serving.
Per serving: 400 calories; 199 calories from fat (50 percent of total calories); 22 g fat (13 g saturated; 0 g trans fats); 66 mg cholesterol; 35 g carbohydrate; 17 g protein; 4 g fiber; 66 mg sodium.
