Preheat the oven to 180°C / 350°F / Gas mark 4. Spread the walnuts out on a baking sheet and roast for 10 minutes, shaking the sheet halfway through, until lightly toasted. When cool enough to handle, roughly chop.

While the nuts are roasting, put the pasta water on to boil. If using dried pasta, start cooking it now; if using fresh, cook once the sauce is ready.

For the sauce, place the butter, garlic and rosemary in a small frying pan and cook over a medium-low heat until everything is gently sizzling and smelling delicious. Be careful not to burn the garlic.

Add the cream, wine and 60ml / 2fl oz of the pasta cooking water and gently bubble away for a minute or so. Add the Gorgonzola and Parmesan and cook gently, stirring, until the cheese has melted. Add more pasta water if needed to make a loose but creamy sauce. Add the lemon zest and a good grinding of black pepper. Taste and add more salt or pepper if you like.

When the pasta is cooked, lightly drain, reserving a good splosh of the cooking water, and return the pasta to the pan. Add the sauce and quickly toss together, then fold in most of the roasted nuts, adding a little of the reserved pasta water if necessary to loosen.

Serve topped with more Gorgonzola, the remaining walnuts and a generous grating of chocolate or finely blitzed cacao nibs.