Place the pine nuts in a dry skillet over medium heat. Stir and flip the nuts frequently for 3-4 minutes until the nuts (uh, technically they are seeds, but whatever) are fragrant and lightly browned. Transfer to a plate and let cool fully.

Add the cooled pine nuts to a food processor. Add the spinach, basil, garlic, lemon juice, salt, and black pepper. Pulse several times until the mixture is finely chopped and begins to form a coarse paste. Scrape down the sides of the bowl as needed so the mixture processes evenly.

With the machine running, slowly pour in the olive oil in a steady stream so the mixture emulsifies and becomes smooth.

Stop the machine and scrape the sides of the bowl. Process again until the sauce reaches a smooth, cohesive consistency. Taste and tweak the seasoning if needed.