Soak the cashews: Cover the cashews with hot water and soak for 15 minutes. Drain well. If you have time, a longer soak (30–60 minutes) makes an even silkier sauce.

Toast the pine nuts: Warm a dry skillet over medium heat. Add pine nuts and toast 2–3 minutes, stirring, until golden and fragrant. Transfer to a plate to cool.

Cook the pasta: Boil in well-salted water until just al dente. Reserve 1 cup pasta water, then drain.

Blend the pesto: In a blender or food processor, add basil, soaked cashews, half the toasted pine nuts, garlic, nutritional yeast, lemon zest, 2 tablespoons lemon juice, 1/4 cup olive oil, 1/3 cup plant milk or water, 1/2 teaspoon salt, and a few grinds of pepper. Blend until very smooth, thinning with more liquid as needed. Taste and adjust lemon, salt, and oil.

Combine: Return pasta to the pot on low heat. Pour in the pesto and a splash of reserved pasta water. Toss until glossy and the sauce clings. Add more pasta water as needed for a creamy, loose coating.

Fold in sundried tomatoes: Stir in chopped sundried tomatoes and a pinch of red pepper flakes if you like heat.

Finish and serve: Top with remaining toasted pine nuts, extra basil, black pepper, and a drizzle of olive oil. Serve warm.