Cook pasta: Boil farfalle pasta in salted water according to package instructions. Drain and reserve ¼ cup pasta water.
Prepare pesto: In a blender or food processor, add basil, spinach, walnuts (or cashews), garlic, olive oil, lemon juice, and salt to taste. Blend until smooth.
Adjust consistency: Add a little reserved pasta water if needed to make the pesto creamy.
Combine: Toss the cooked farfalle with the dairy-free pesto until evenly coated.
Simmer briefly: Cook on low heat for 1–2 minutes to allow flavors to combine.
Taste & adjust: Adjust seasoning or lemon juice if needed.
Serve: Serve warm or at room temperature, optionally topped with toasted nuts or chili flakes.