I use a similar technique here that I use when making sauces with clams, which is to finish cooking the pasta in the sauce with the juices the mussels release when they open allowing the pasta to soak up all their flavor.
4tablespoonsextra virgin olive oil
1teaspoongarlic, finely chopped
⅛teaspooncrushed red pepper
1tablespoonflat leaf Italian parsley, finely chopped
¼cupdry white wine
1cupfresh tomatoes, peeled, seeded and ½-inch diced
40fresh, live mussels
2tablespoonsfresh basil, shredded
Fill a pot for the pasta with about 6quarts of water, cover, and place over high heat.
Put 3tablespoons of the olive oil in a deep skillet large enough to accommodate all the mussels and cooked pasta later, and place over medium high heat. Add the garlic, crushed red pepper and the parsley. Once the garlic is sizzling, add the white wine and cook for 1 to 2 minutes until the alcohol has evaporated. Add the tomatoes and season with salt. Cook stirring for 2 to 3 minutes until the tomatoes begin to soften.
Add 2tablespoons salt to the boiling pasta water, add the spaghetti, and stir until all the strands are submerged. Cook until very al dente.
Add the mussels to the pan with the sauce, stir well, and cover. Cook until all the mussels have opened. Don’t be too quick to discard mussels that do not open. The more stubborn ones are usually the freshest. Add the basil and remove from the heat.
When the spaghetti are cooked about a minute less than al dente, return the pan with the mussels to a medium heat. Drain the pasta and add it to the pan letting the spaghetti finish cooking in the pan. When done, there should be just a little amount of liquid left. You can control how much liquid is left by either covering the pan, or leaving it uncovered as the pasta finishes cooking.
Toss in the remaining tablespoon of olive oil and serve at once with the mussels in the shell.