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 water before draining.
02 - Combine avocados, spinach, basil, garlic, pine nuts, Parmesan, lemon juice, and olive oil in a food processor. Season with salt and pepper.
03 - Process until completely smooth and creamy, scraping down sides as needed. Add 1-2 tablespoons pasta water if mixture is too thick.
04 - Toss drained spaghetti with pesto sauce, adding reserved pasta water as needed to coat noodles evenly.
05 - Plate immediately topped with extra Parmesan, fresh basil leaves, and cracked black pepper.