Bring 6 quarts water to a rolling boil
and add 2 tablespoons salt.
Heat the olive oil over a medium flame until hot but not smoking. Add the garlic, chicken livers, peas, salt, to taste, and cook until the meat is browned and the peas are soft, about 7 minutes.
While the meat browns, add the perciatelli to the boiling water and cook, according to the package directions, until tender but still al dente
Meanwhile, reheat the Ragu alla Napoletana in a separate saucepan
the cooked pasta
and add to the saucepan with the ragu. Add the chicken livers and peas and toss over high heat until the ingredients are well combined. Add the chili flakes and the mozzarella and toss again, so the mozzarella melts amidst the noodles
. Serve immediately in 4 warmed pasta bowls. Garnish
, to taste, with the Parmigiano.