Classic Pesto (with basil and pine nuts)

0 Toast pine nuts (optional): Place a dry skillet or frying pan over medium heat. Add pine nuts and cook, stirring frequently, until they start to smell fragrant and lightly golden brown spots appear, 3 to 4 minutes. (Watch the pine nuts closely to prevent burning.)
1 Make pesto: Combine pine nuts, basil leaves, garlic cloves, cheese, salt, and lemon juice in the bowl of a food processor. (Note: You can also use a standing blender if the blades sit low enough to blend the ingredients.) Pulse / blend until all of the ingredients are finely chopped.
2 With the food processor running, slowly pour in the olive oil until the pesto is smooth and pourable. If it is too thick, you can add up to 1 Tablespoon of additional olive oil. 
3 Taste the pesto and season with some more salt, if needed.