Place pine nuts in a skillet over medium-low heat. Stir or toss frequently until toasted. Cool before using.
Place basil, pine nuts, and garlic in food processor or blender. Pulse until finely chopped. With motor running, slowly drizzle in olive oil. Blend a few minutes, stopping occasionally to scrape sides, until smooth.
Stir in grated Parmesan. Taste for seasoning and add salt and pepper to taste, if desired. Yields about 1 1/4 cup pesto.