Heat oven to 400°.
Coat the interior of a 1 1/2-quart gratin or baking dish with the softened butter and spoon in the 2 tablespoons of bread crumbs; tilt the dish around until they cover the buttered surface.
Slice the chard stems and leaves into 1 1/2-inch pieces; wash in cold water; drain but don't dry them.
Heat the olive oil in a 6-quart Dutch oven or soup pot over medium heat; add the shallot and garlic; cook, stirring constantly, until softened but not browned, about 1 minute; add the chard, sprinkle with salt; cover tightly and steam until the chard has wilted to half its original volume, about 2-3 minutes; uncover and cook the chard, turning occasionally with tongs, until all the water in the pan evaporates, about 5 more minutes; season with pepper and set aside.
Sauce - melt the butter in a small saucepan over medium heat; whisk in the flour; cook, whisking, until mixture bubbles up and turns lighter in color, about 1 minute; pour in the cold milk all at once; whisk vigorously; add salt and bay leaf; heat, whisking, until it comes to a boil and thickens, about 5 minutes; reduce the heat to low, simmer 2 minutes; stir in the nutmeg, oregano, thyme and 1/2 cup of the cheese; remove from heat and discard bay leaf.
Mix the cooked chard and the sauce; spoon into prepared pan; sprinkle with remaining 1/4 cup bread crumbs and remaining 1/2 cup cheese; bake until golden and bubbly, 35 minutes.