How to Make It
In a food processor, pulse the bread until crumbs form; you should get about 1/3 cup. In a small skillet, heat 2 tablespoons of the olive oil. Add the crushed garlic and cook over moderately low heat until the oil is infused with garlic flavor, about 10 minutes. Add the bread crumbs and cook, stirring occasionally, until golden and crisp, 7 to 8 minutes. Season the bread crumbs with salt.
Cook the spaghetti in a large pot of salted boiling water until almost al dente (you will cook it more later). Drain the spaghetti, reserving 1 cup of the cooking water.
Meanwhile, in a large skillet, heat the remaining 1/2 cup of olive oil. Add the anchovies and the sliced garlic and cook over moderately low heat, stirring occasionally, until the anchovies have dissolved and the garlic has softened, about 5 minutes. Stir in the crushed red pepper.
Add the pasta, 1/2 cup of the pasta cooking water and the parsley to the skillet and toss until the pasta is well coated in the sauce (add more pasta water if it seems dry). Season with salt and black pepper. Serve the pasta in bowls, sprinkled with the bread crumbs.