In a medium saucepan over medium, bring 6 cups water, covered, to a simmer. Reduce to low to keep warm. In a large saucepan over medium, melt 1 tablespoon of the butter; add the bread and cook, stirring, until browned and crisp, 6 to 8 minutes. Add the rosemary and cook, stirring, until fragrant, about 30 seconds. Transfer to a bowl and stir in the parsley; set aside. Wipe out the saucepan.

In the same saucepan over medium, melt 1 tablespoon of the remaining butter. Add the sausage and cook, breaking it into small pieces, until no longer pink and beginning to brown, 5 to 6 minutes. Using a slotted spoon, transfer to a small bowl; set aside. To the fat remaining in the pan, add the onion and ¼ teaspoon each salt and pepper. Cook over medium, stirring occasionally, until softened, about 3 minutes.

Add the rice and cook, stirring, until the grains are translucent at the edges, 1 to 2 minutes. Add the wine and cook, stirring, until most of the liquid is absorbed, 1 to 2 minutes. Add 2 cups of the hot water and bring to a boil over medium-high. Reduce to medium and simmer, stirring often and briskly, until most of the liquid is absorbed, 8 to 10 minutes. Add another 2 cups hot water and cook until most of the liquid is absorbed and the rice is tender, with just a little firmness at the center of the grains, 6 to 9 minutes.

Off heat, quickly stir in the sausage and any accumulated juices, the remaining 1 tablespoon butter and the Parmesan; it’s fine if the butter and cheese do not fully melt. Cover and let stand 10 minutes. (Reserve the remaining hot water in the saucepan for adjusting the consistency of the risotto at the end, if needed.)

Stir to fully incorporate the butter and cheese. If the risotto is stiff and dry, stir in additional water, a couple tablespoons at a time, until the risotto is loose but not soupy. Taste and season with salt and pepper. Serve immediately, sprinkled with the breadcrumbs and additional Parmesan.