Bring a large pot of lightly salted water to a boil. Add the spaghetti, and cook until al dente, or 8 to 10 minutes. Drain, and rinse under cold water. Toss with 1/4 cup olive oil, cover and keep warm.
Place another 1/4 cup olive oil in a skillet, and heat over medium heat. Stir in the garlic, and cook just until golden, 2 to 3 minutes. Add the sardines, and cook 1 minute more. Stir in the bread crumbs and 1/3 cup Parmesan cheese. If necessary to give the mixture a crumbly texture, stir in the remaining 1/4 cup of olive oil. Stir in the parsley and pepper, and remove from the heat. If desired, serve with additional Parmesan cheese.