Pine nuts add a signature nutty richness to traditional pesto, but they aren’t essential to make a delicious sauce. Their creamy texture and mild flavor help balance the sharpness of the garlic and basil, but you can easily substitute them with alternatives like sunflower seeds, pumpkin seeds, or even skip them altogether. The key flavors in pesto also come from the basil, garlic, olive oil, and parmesan, so pine nuts are important but not irreplaceable!