Heat oil over high heat in a large frypan. Brown chicken. Reduce heat, and add garlic and mushrooms. Cook until soft. Remove chicken and mushrooms from the frypan.
Pour cream into frypan and bring to a boil over high heat. Reduce heat to medium, and reduce cream. Stir occasionally.
Meanwhile, cook the pasta in a large pot of boiling water until done. Drain.
When cream has reduced and thickened, stir in Gorgonzola until melted. Add chicken and mushrooms, pasta and walnuts. Toss and reheat. Season with salt and pepper. Serve immediately. Garnish with freshly grated Parmesan cheese, if desired.