Bring a medium pot of water to a boil. Prepare an ice-water bath and set aside. Place spinach leaves and basil in a colander or strainer; pour boiling water over spinach and basil. Immediately transfer to ice-water bath to cool. Squeeze leaves together to extract as much water as possible.
Transfer spinach and basil to the bowl of a food processor along with cheese, garlic, olive oil, and pine nuts. Process until a smooth paste is formed; season with salt and pepper. Use immediately or store in an airtight container, refrigerated, for up to 5 days.
Contributors' Comments Add Comment