Place the basil, spinach, parmesan cheese, garlic, lemon zest and lemon juice in a food processor or heavy duty blender. Pulse for 1 minutes to break everything up.

Slowly stream in the olive oil while the motor is running. Once everything is incorporated, turn off the blender or food processor and season with salt and pepper. Adjust as needed and transfer the pesto to air tight containers to refrigerate or freeze until ready to use.