Trim, wash, and slice one medium leek. Shell 1 pound medium shrimp and devein. Cut them in bite-sized pieces. Heat 2 tablespoons extra virgin olive oil in a large skillet over medium heat. Add leek, stirring until tender, about 4 minutes. Increase the heat under the pan to high, toss in the shrimp and cook, stirring constantly, until bright pink and seared on all sides, about 2 minutes. Remove from heat and set aside.

Heat stock and keep over low heat. For creamy risotto, with grains separate and al dente, you are coaxing the starch gently out of the grains of rice. Adding cold stock to the risotto may cause the surfaces of rice to seize up and seal in the starch, instead of releasing it into the liquid.

Heat 3 T olive oil in a wide 3 to 4-quart braising pan over medium heat. Add onion and cook, stirring occasionally, until softened, about 4 minutes. Stir in the leek and white parts of the scallions and cook, stirring, until the onion is golden, about 6 minutes.

Stir in rice until the grains are coated with oil and toasted - the edges translucent - 1 to 2 mins. Pour in the wine and let it boil, stirring the rice, until evaporated. Since rice is 98 percent starch, the acidity in the wine balances and imparts flavor to the rice kernel.

Season lightly with salt and ladle enough stock to barely cover rice. Bring to a boil, then reduce to simmer, stirring constantly, until all the stock has been absorbed and you can see the bottom of the pan when you stir. Continue cooking, pouring in the remaining hot stock in small batches-each additional should be just enough to completely moisten the rice-and cook until each batch of stock had been absorbed. Stir constantly until the rice mixture is creamy but al dente; this will take 16 to 20 minutes from the time the wine was added.

Adjust heat throughout so rice simmers gently. For creamier risotto stir in a little more stock once the rice is al dente, but do not cook the rice any further. For a denser risotto, keep rice over the heat and cook until the last addition of the stock has been almost entirely absorbed by the rice. (Generally risotto with seafood is looser and risotto prepared with meats and mushrooms is more dense.) Stir in the leek and shrimp in the last 2 minutes of cooking.

Remove pan from heat; stir in pepper, butter and green parts of the scallion until the butter is completely melted. Stir in half the grated cheese, taste and adjust seasonings. Ladle risotto into warm, shallow bowls and serve immediately after finishing. Either top each serving with some of the remaining grated cheese or pass the cheese separately.