In a large pot of boiling water, cook the spaghetti for 8-10 minutes or until al dente. Drain well, return the cooked spaghetti to the pot, and set aside. Meanwhile, in a large non-stick skillet, place the walnuts, and toast over medium heat for 2-3 minutes or until fragrant. Remove the walnuts from the skillet and set aside to cool. In the same skillet, saute the mushrooms in the olive oil for 3 minutes or until just tender. Add the soy milk, pesto, nutritional yeast flakes, and pepper, and simmer the mixture for 2-3 minutes while stirring occasionally. Add the cooked spaghetti and toss well to coat with the sauce. Roughly chop the toasted walnuts. Add the chopped walnuts, along with the remaining ingredients, and toss lightly to combine. Transfer to a large bowl or platter for service.

Serves 6-8