Makes 4 servings

Wash and stem: 1 1/2 bunches chard
Save half the stems and slice them thinly. Cook for about 2 minutes, in: 2 quarts boiling salted water
Add the chard leaves and cook until tender, about 3 minutes. Drain and cool. Gently squeeze out the excess liquid from the stems and leaves and coarsely chop them.
Prepare: 1 cup breadcrumbs
Toss with: 2 teaspoons butter, melted
Toast on a baking sheet in a 350°F oven, stirring now and then, until lightly brown, about 10 minutes.
Melt over medium heat in a heavy-bottomed pan: 1 1/2 tablespoons butter
Add: 1 onion, diced
Cook over medium heat, until translucent, about 5 minutes. Stir in the chard and: 1 teaspoon salt
Cook for 3 minutes. Sprinkle over: 2 teaspoons flour
Stir well and add: 1/2 cup milk
A little freshly grated nutmeg
Cook for 5 minutes, stirring occasionally. Add more milk if the mixture gets too thick. The chard should be moist but not floating in liquid. Taste and add salt if needed.
Butter a small baking dish. Spread the chard mixture evenly in the dish and dot with: 2 teaspoons butter
Sprinkle the breadcrumbs evenly over the top. Bake in a 350°F oven until the gratin is golden and bubbling, 20 to 30 minutes.