PREPARATION
Bring a large pot of well-salted water to a boil. Add the Rigatoni and cook until al dente, according to package directions. Reserve 1½ cups pasta cooking water, and drain.
Heat a 12-inch skillet over medium heat. Toast the hazelnuts, stirring frequently so they do not burn, about 4 to 5 minutes. Remove and set aside and wipe out the skillet with a paper towel.
Heat the olive oil in the 12-inch skillet over medium heat. Add the Radicchio SIPO and cook until it begins to wilt and browns in spots, about 4 minutes. Season with salt and pepper. Stir in the gorgonzola and 1/2 cup pasta water, and simmer for 1 to 2 minutes more. The water should emulsify the cheese and create a velvety texture.
Add Rigatoni to the skillet and toss to combine with the sauce, adding 1/4 cup pasta water or more as needed until it’s glossy with sauce, about 1 minute more. Add the hazelnuts and half the parsley and toss again to combine. Top with remaining parsley and season with flaky salt. Pass grated cheese at the table, if desired.