Heat the broth in a saucepan and keep it warm on a low flame.
In a large skillet, heat olive oil over medium heat. Add the chopped onion and sauté until translucent, about 3-4 minutes.
Add the minced garlic and cook for another minute, stirring frequently to avoid burning.
Remove the sausage from its casing and add it to the skillet, breaking it up with a spoon as it cooks.
Add the mushrooms to the skillet and sauté until they release their moisture and become golden, about 5 minutes.
Stir in the Arborio rice and cook for 1-2 minutes until it becomes slightly translucent around the edges.
Pour in the white wine and cook until it’s mostly evaporated, stirring frequently.
Begin adding the warm broth, one ladle at a time, stirring often until absorbed before adding more.
Continue adding broth and stirring until the rice is al dente, about 18-20 minutes.
Stir in the Parmesan cheese and butter, mixing until melted and incorporated, and season with salt and pepper to taste.
Let the risotto sit for a minute before serving, then adjust seasoning if necessary.