Heat the broth and keep it hot, but not boiling.

In a wide soup pot or Dutch oven over medium heat, add 2 tablespoons olive oil and 2 tablespoons butter and sauté the onion until soft and clear. Break apart the sausage and sauté for a few minutes until nicely browned. Remove the sausage to a plate and set aside.

Add the rice and cook, stirring, for a minute or two, until it is well-coated and has turned opaque. Increase heat to medium-high and add a quarter of the wine; cook, stirring, until the wine has been completely absorbed and starts to caramelize. Repeat three more times with the remaining wine. When the wine is used up and absorbed, add the hot broth a ladleful at a time, stirring until almost fully absorbed before adding the next ladleful of broth. After about 18 minutes, all the broth should be used up, and the risotto done. The risotto should not be dry and gummy, but have a good “wave” when the pan is shaken. “Al ondine” is the term in Italian — to the wave.

Stir in the cooked sausage, season to taste with salt and pepper. Stir in the remaining 3 tablespoons butter and Parmigiano-Reggiano, stirring them in to melt; this addition is called the mantecatura.

Remove from the heat, serve at once on warm plates with freshly ground black pepper and additional grated Parmigiano-Reggiano.