There are many recipes, with or without pine nuts, walnuts, etc.
Every recipe will contain basil, 1-2 garlic cloves, parmesan cheese, and virgin olive oil:

Basic recipe:
3 cloves of garlic
¼ cup of nut of choice (pine nuts, walnuts, or pistachios)
½ cup of grated parmesan cheese
2 cups of basil leaves
¼ cup extra virgin olive oil
Salt to taste

Add the garlic, nuts and cheese to a food processor and run briefly
Add basil, run processor until a paste-like consistency is reached
Add oil while processor is running
Add salt to taste.