Bring 8 quarts of water to a boil and add 2 tablespoons salt.
In a 14 to 16-inch frying pan, heat oil over medium heat until smoking. Add the garlic and cook until light golden brown, about 2 to 3 minutes. Add the bread crumbs, walnuts and chile flakes and cook until lightly toasted, about 3 to 4 minutes. Remove from heat and set aside.
Drop the pasta into the boiling water and cook according to the package instructions, until 1 minute short of al dente. Just before draining the pasta, add 1/4 cup of the pasta cooking water to the pan with the walnut mixture. Drain the pasta in a colander and pour the pasta into the pan with the walnut mixture. Place the pan over medium heat and continue cooking the pasta with the walnut mixture until the bucatini are tightly dressed with the condiment, about 1 minute. Add the parsley and grated cheese, stir through, pour into a heated bowl, and serve immediately.