01 - Bring a large pot of salted water to a rolling boil. Add the penne or fusilli pasta and cook according to package directions until al dente. Before draining, reserve 1/2 cup of the pasta cooking water. Drain the pasta and set aside.
02 - While the pasta is cooking, combine the fresh basil leaves, pine nuts (or walnuts), garlic cloves, grated Parmesan cheese, extra virgin olive oil, a pinch of salt and freshly ground black pepper, and the juice of 1/2 lemon in a food processor. Process until a smooth pesto is formed, scraping down the sides of the bowl as necessary.
03 - Heat a large skillet over medium heat. Add a splash of olive oil and sauté the diced zucchini for 2 to 3 minutes, or until it just begins to soften. Incorporate the peas and baby spinach leaves; continue cooking for an additional 2 minutes until the spinach wilts and the peas are bright green.
04 - Add the drained pasta and the freshly made pesto to the skillet with the sautéed vegetables. Toss thoroughly to ensure the pasta is evenly coated. If a creamier consistency is desired, gradually add the reserved pasta water, a tablespoon at a time, until the preferred texture is achieved. Stir in the sliced scallions. Serve immediately, garnished with extra grated Parmesan cheese, fresh basil leaves, and a sprinkle of lemon zest.