Jerusalem artichokes harmonize well with other autumnal ingredients, as in this gratin of sunchokes, chestnuts, and Yukon gold potatoes that's thickened with creme fraiche and Gruyere.
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.