Grow 4-5 large basil plants so you can make this all summer long. Purple basil makes the spiciest pesto (my Dad's favorite).
Put basil, nuts, cheese and garlic in a food processor.
Turn it on and drizzle in enough olive oil to reach the desired consistency - thick for spreading on bread or thin for tossing with cooked vegetables or pasta.
NOTE: Do not use dried basil. This recipe can be frozen (in ice cube trays or 1/2 - 1 cup portions) for up to 6 months, but do not add the cheese until you are ready to eat or the sauce will fall apart.