01 - Bring a large pot of salted water to a boil. Cook the spaghetti according to package instructions until al dente. Reserve 1/2 cup of pasta cooking water, then drain the spaghetti.
02 - While the pasta cooks, 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 - Blend until smooth and creamy, scraping down the sides as needed. If the mixture is too thick, add 1–2 tablespoons of pasta water to reach your desired consistency.
04 - Toss the drained spaghetti with the pesto, adding a splash of reserved pasta water as needed to coat the noodles evenly.
05 - Serve immediately, garnished with extra Parmesan, fresh basil leaves, and a sprinkle of cracked black pepper.