How to Make It
Coarsely chop the chard leaves. Peel any strings from the thick stems as you would celery, then cut the stems into 1-inch pieces.
Bring a large pot of salted water to a boil. Meanwhile, in a heavy medium skillet, melt the butter in the olive oil. Add the shallots and cook over moderate heat, stirring occasionally, until softened, about 5 minutes. Season with 1/2 teaspoon each of salt and pepper.
Add the chard stems to the boiling water and cook until tender, about 5 minutes. Using a slotted spoon, transfer to a bowl. Add the leaves to the pot and cook until tender, about 2 minutes. Drain well in a colander and transfer to another bowl.
Rewarm the shallots. Stir half into the chard stems and half into the leaves and season both with salt and pepper. Make a ring of the stems on a large platter and pile the leaves in the center.