Bring a large pot of salted water to a boil for the pasta.
Put the butter in a medium skillet over medium-low heat. As it melts, crumble the sausage meat into it, making the bits quite small, ½ inch or less. Add the liquid, and adjust the heat so that the mixture simmers gently.
3 Cook the pasta until it is tender. Reserve about ½ cup of the pasta cooking water.
Drain the pasta, add the sauce, adding a little of the reserved cooking liquid if necessary. Toss with salt, pepper and Parmesan, and serve.
