This is a wonderful, inexpensive dish that's great for a crowd. The broth-like sauce is light, yet full of great flavor. I choose not to add any butter, but rather use the lighter taste of olive oil for the fat in this dish. A word of caution: this recipe feeds about 6, but takes up a lot of room, especially once the mussels are all opened in their shells. I gave a small hint at the end of how one might serve this without overflowing their bowl. You might also like to spoon the pasta into individual serving bowls, and then top each one with mussels and broth, whichever you prefer. Use your best judgment!