Bring the stock to a simmer in a medium saucepan over high heat. Reduce the heat to very low to keep the stock hot.
Heat the oil in a large heavy saucepan over medium-high heat. Add the onions and garlic. Cook, stirring often, until the onions soften, about 3 minutes. Add the rice and cook, stirring constantly, until the grains are opaque, about 2 minutes. Add the wine and stir until it evaporates, about 1 minute. Add the saffron. Add 3/4 cup of the stock and cook, stirring, until it has been absorbed by the rice. Continue to cook and stir, adding 1/2 cup of the stock at a time as the liquid is absorbed by the rice.
When the rice is almost tender, after about 20 minutes of stirring and adding stock, stir in the shrimp, cream, green onions, and butter. Continue cooking, adding more stock (or water) as needed, until the rice is just tender and creamy and the shrimp have turned pink, 3 to 4 more minutes.
Remove from the heat and stir in the cheese. Season with the salt and pepper. Serve immediately.
Yield: 8 appetizer or 4 main-course servings