Prepare the bread. Using day old rustic italian bread, tear the inside portion (not the hard crust) into small pieces. The bread should be quite dry. Set aside.
Bring a pot of salted water to boil.
Meanwhile, heat the olive oil and garlic in a pan over low-medium heat.
Remove garlic clove. Add the breadcrumbs to the pan and fry for a few minutes.
Add the chopped walnuts and cook until it is all toasted and golden brown. Add salt and red pepper flakes to taste.
Cook the pasta. Transfer with a slotted spoon to the pan. Toss in the breadcrumbs. Add a little bit of pasta water if it seems too dry.