Preheat oven to 350 degrees F (175 degrees C). Butter a 2-quart baking dish.
Bring water to a boil in a large saucepan, and sprinkle in the rice. Stir, reduce heat to low, and simmer the rice until it is half-cooked, about 5 minutes. Drain the rice, and set aside.
Melt the butter in a large skillet over medium heat, and cook and stir the onions until translucent but not browned, about 8 minutes. Mix the cooked onions and the butter from the skillet with the rice, and stir in the half-and-half, salt, and 1 3/4 cup of the Swiss cheese. Transfer the mixture to the prepared baking dish, and sprinkle the remaining 1/4 cup of Swiss cheese over the top.
Bake uncovered in the preheated oven until the rice is tender and the top is lightly browned, about 1 hour.