Combine the basil, parsley, walnuts, and cheese in a food processor or mortar. Pulse or grind gradually adding the 3 cups olive oil until the mixture forms a paste.

Bring a large pot of salted water to a boil over high heat. Add the linguine and cook until it is al dente, about 8 minutes; drain and reserve.

Heat 3 tablespoons of oil in a large skillet over high heat. Add the scallops, mushrooms, and zucchini and cook until the vegetables are tender and the scallops are opaque, about 2 minutes. Add the pesto and the linguine. Toss to coat the pasta with sauce. Spoon onto warm plates and serve.