Set aside 1/2 pound of the nicest chard stems; reserve the rest for another use. Bring 2 inches of water to a boil in a large stockpot. Add the 1/2 pound of chard stems and cook until almost tender, about 4 minutes. Using tongs, transfer the stems to a plate to cool. Add the chard leaves to the boiling water in batches, adding more as each batch wilts. When all the leaves have been added, cook for 1 minute. Drain the chard leaves; let cool, then squeeze dry and coarsely chop. Cut the stems into 1-inch pieces.
Melt the butter in a large enameled cast-iron casserole. Add the onion and jalapeños and cook over low heat until softened, about 10 minutes. Add the garlic and cook, stirring, until fragrant, about 2 minutes. Add the curry powder and cook, stirring, for 2 minutes longer. Add the cream and simmer over moderately high heat until reduced to 3/4 cup, about 10 minutes. Remove from the heat and let cool to room temperature. Stir in the chard leaves and stems and season with salt and pepper.
Meanwhile, in a small saucepan, cover the rice with the water and bring to a boil. Cover and cook over low heat until the water has been absorbed, about 12 minutes. Fluff the rice.
Preheat the oven to 350°. Cut the tops off the bell peppers, leaving a 1/2-inch ring of pepper around each stem. Scoop out the seeds and ribs. Stand the peppers in a large baking dish or roasting pan and rub the skins with olive oil. Season the insides of the peppers with salt and pepper and spoon a scant 1/4 cup of rice into each one. Fill the peppers with the creamed chard and replace the tops; oil the tops. Bake for about 1 hour, or until the peppers are tender and the filling is hot.
Make Ahead: The stuffed peppers can be refrigerated overnight. Bring to room temperature before baking.