Ingredients
1 pound Jerusalem artichokes (about 10 small), peeled, sliced 1/4 inch thick, and reserved in cold water (drain and pat dry before using)
3 cups milk
8 ounces creme fraiche
2 tablespoons freshly squeezed lemon juice
1 cup grated Gruyere cheese (4 ounces)
1 tablespoon minced fresh thyme
1 1/2 teaspoons coarse salt
1/4 teaspoon freshly ground pepper
1/2 pound Yukon gold potatoes, peeled and sliced 1/4 inch thick
5 ounces shallots (about 4), thinly sliced
5 ounces jarred or vacuum-packed peeled chestnuts, halved lengthwise
4 slices white bread, trimmed of crusts, lightly toasted and torn into small pieces
Preparation
Preheat oven to 450 degrees. In a large saucepan, bring artichokes and milk just to a boil. Reduce heat; simmer until crisp-tender, about 10 minutes. Drain in a colander set over a bowl; reserve 3/4 cup milk.
In a large bowl, whisk reserved milk with creme fraiche, lemon juice, 1/4 cup cheese, thyme, salt, and pepper. Add artichokes, potatoes, shallots, and chestnuts; stir to combine.
Pour mixture into a 1 1/2-quart gratin dish; cover tightly with foil. Bake on a baking sheet until artichokes are tender when pierced, about 1 hour. Remove foil; sprinkle top of gratin with bread pieces and remaining 3/4 cup cheese. Continue baking, uncovered, until golden brown, 8 to 10 minutes more. Serve warm.
