Bring the broth, cream and garlic to the boil in the saucepan and reduce by half. Toast the chopped walnuts in a dry pan a little. Cook the spaghetti according to the instructions on the packet and then drain.
Dissolve the Gorgonzola in the sauce. Season to taste with lemon juice and zest. Stir in the spaghetti and heat. Mix in the parsley and raspberries. Spread on 2 plates, sprinkle with the roasted nuts and grind the pepper over them.