01 - Bring a large pot of salted water to a boil. Cook spaghetti according to package directions until al dente. Reserve 1/2 cup pasta cooking water before draining.
02 - Combine avocados, spinach, basil, garlic, pine nuts, Parmesan, lemon juice, and olive oil in a food processor or blender. Season with salt and pepper.
03 - Process until smooth and creamy, scraping down sides as needed. If too thick, add 1-2 tablespoons pasta water to achieve desired consistency.
04 - Toss drained spaghetti with pesto, adding reserved pasta water as needed to coat evenly. Serve immediately garnished with extra Parmesan, fresh basil, and cracked black pepper.