In a large pan of boiling salted water, cook your pasta shapes to the packet instruction until cooked.
While the pasta cooks, add the guanciale to a deep sauté pan then turn to heat to moderate. Let the guanciale gradually start to sizzle and render out its fat (about 4-5 minutes)
Add the onion to the pan and let this cook for 3-4 minutes until soft and golden.
Add the radicchio leaves and walnuts and stir for 1-2 minutes to wilt and cook the radicchio. Remove from heat until your pasta cooks.
When the pasta is cooked, return the sauce to the heat and add the hot pasta along with 1 ladle of the pasta water and the gorgonzola cheese.
Stir quickly to incorporate everything and create an emulsifies creamy sauce. Add a little more pasta water if needed. Season with pepper then taste and add a little salt if needed.
Spoon into bowls and serve immediately.
Notes
Serving Suggestions:
Serve immediately while hot to maintain a creamy sauce; prolonged sitting absorbs the sauce into the pasta.
If you prefer a different blue cheese, be cautious not to overpower the sauce. Consider substituting with Mascarpone or Camembert for a luxurious creamy touch.
No Radicchio? Substitute with chicory or other bitter greens like spinach, cavolo nero, or chard.
In the absence of guanciale, use Italian pancetta, unsmoked salty bacon, or salt pork.
If you don't have walnuts, pecans or hazelnuts can be used as alternatives for this dish.
Storage Suggestions:
Ideally, consume fresh, but refrigerate any leftovers for 1-2 days.
To reheat, add a little water to maintain creaminess in the sauce.
Freezing is not recommended for this particular dish.