Preheat oven to 325F.
Place walnuts on a baking sheet and transfer to the oven to toast them up, about 10-12 minutes (your nose will know when they are done).
In a medium-size skillet over medium heat, melt 1 tablespoon of butter with the EVOO. Add the onions and cook until tender, about 2-3 minutes.
Add mushrooms and garlic, and brown, about 4 minutes.
Add the spaghetti and toast until golden brown, about 5 minutes. Season with salt and ground black pepper then stir in the white wine. Stir continuously as it absorbs then add in a ladleful of stock. Keep stirring as that absorbs. Continue the process until the spaghetti is tender and cooked through.
To finish, stir in the sage, remaining tablespoon of butter and half the gorgonzola. Garnish each portion with more gorgonzola crumbles and some of the toasted walnuts.