Begin by washing the spinach leaves or soaking them in a solution of 10% vinegar to water for 10 minutes. Rinse well.
Add to the food processor or blender.
Place the pine nuts in a dry skillet over medium heat for 5 minutes, stirring often to prevent burning. Add spinach leaves.
Finely chop garlic and add, then the cheese, salt, and pepper.
Start processing the mixture.
While the processor is running, slowly add the olive oil.
Add the lemon juice, and stir.
Serve at once over hot pasta, or store in the fridge for up to 2 weeks, or the freezer for up to 6 months.