2 tablespoons unsalted butter 2 tablespoons olive oil 1 medium onion, finely chopped 1 pound Arborio rice 6 cups chicken stock, hot 2 tablespoons butter 3 ounces Parmagiano Reggiano cheese, coarsely grated|Heat the butter and oil in a large, straight−sided saute pan or saucepan. Add the onion, and saute until soft, without browning. Add the rice, and saute for 2 minutes until the rice is well−coated. Ladle 1/2 cup of stock into the rice, stirring constantly, until all the liquid is absorbed and the rice is almost dry. Add more stock, 1/2 cup at a time, until it's all absorbed by the rice and the rice is al dente. The rice should be very moist and creamy, but not runny; the rice should be firm but tender, not crunchy. Remove from heat, and stir in the raw butter and the Parmagiano cheese. Salt to taste, and serve immediately.