Preparation

• Position a rack in the center of the oven and heat to 375°F. Strip the leaves off the chard stalks, and set the stalks aside. Fill a large saucepan about two-thirds full of water and bring to a boil over high heat. Add half of the chard leaves and cook, stirring, until wilted, about 1-1/2 minutes. Remove the leaves from the water with a slotted spoon, transfer to a bowl, and repeat with the remaining leaves. Rinse the leaves under cold water; then, working in two batches, squeeze the leaves with your hands to remove excess water (do not wring in a towel). Coarsely chop the leaves. Rinse out the pan.
• Thinly slice the chard stalks crosswise. In the same pan, melt 1/2 Tbs. of the butter over medium heat, add the stalks, and cook, stirring occasionally, until crisp-tender, about 6 minutes; spread in the bottom of a 1-1/2-quart casserole.
• Melt 1-1/2 Tbs. of the butter in the saucepan over medium heat. Add the shallots, 1/2 tsp. salt, and 1/4 tsp. pepper, and cook, stirring often, until tender but not browned, about 4 minutes. Add the flour and cook, stirring, until thickened slightly, about 1 minute. Gradually whisk in the warm broth. When all of the broth has been added, bring to a simmer and cook, stirring constantly, until slightly thickened, about 5 minutes. Stir in the chopped chard leaves and cook, stirring, until heated through and the liquid is slightly reduced, 1 to 2 minutes. Season to taste with
  salt and pepper. Spread the chard mixture evenly in the casserole.
• In a small saucepan, melt the remaining 3 Tbs. butter. Put the bread slices in a medium bowl and drizzle half of the butter on top; toss well and repeat. Sprinkle the cheese on top and toss again. (You can prepare the casserole to this point two days ahead. Cover the casserole and bread topping separately and refrigerate. Let the chard stand at room temperature before baking.) Arrange the cheesy bread on top of the chard in the casserole; sprinkle any cheese remaining in the bowl on top. Bake until the bread is nicely toasted and crisp, about 20 minutes. Tent loosely with foil and bake about 5 minutes more, or until the center of the chard mixture is piping hot. Serve warm.