As a note, to toast the pine nuts, I add mine to a skillet and heat over low heat. I shake and stir until they are golden and fragrant, about 5 to 6 minutes. Do not walk away! They burn quickly.
To make the pesto, combine the basil, avocado, cheese, lemon juice, pine nuts, and garlic in a food processor. Add a big pinch of salt and pepper along with the crushed red pepper. Pulse until small crumbs remain, and then with the processor running, stream in the olive oil. Start with the ½ cup and add any extra if needed to reach the desired consistency. Taste and season additionally with salt if needed.
Bring a pot of salted water to a boil and cook the bucatini according to the directions. Reserve 1 cup of starchy pasta water.
Drain the pasta and toss it back in the pot. Add the pesto while it’s hot and toss it thoroughly so every noodle is coated. Stir in a sprinkle of extra cheese, some fresh basil leaves, and crushed red pepper. Serve immediately with a wedge of lemon for spritzing!
