Serves 4 to 6
1 cup walnuts, toasted
1/2 cup heavy cream or vegetable broth
2 tablespoons extra virgin olive oil
1 tablespoon unsalted butter
1 yellow onion, thinly sliced
2 cloves garlic, thinly sliced
6 ounces cremini mushrooms, sliced
6 ounces button mushrooms, sliced
2 tablespoons mirin or water
6 tablespoons chopped parsley
1 pound dried spelt spaghetti
Put 3/4 cup of the walnuts and heavy cream into a blender and puree until smooth. Set aside. Heat oil and butter in a large skillet over medium heat. Add onions and cook until translucent, 6 to 8 minutes. Add garlic and mushrooms and raise the heat. Cook, stirring often, until mushrooms release their juices, 2 to 3 minutes. Reduce heat to low, add mirin and simmer, covered, for 10 to 12 minutes. Add 1/4 cup of the parsley and reserved cream-walnut mixture to the sauce. Simmer lightly, 2 to 3 minutes, until the sauce is thickened.
Meanwhile, cook spaghetti according to package directions. Drain well and transfer to a large bowl. Pour sauce over pasta, toss to coat and garnish with remaining 1/4 cup walnuts and 2 tablespoons parsley. Serve immediately.