Wash basil leaves gently and pat them completely dry
Remove stems and discard damaged leaves
Freeze whole leaves in a single layer on a baking sheet
Transfer frozen leaves to an airtight freezer bag or container
Or chop basil and mix it with a little olive oil
Spoon the mixture into ice cube trays and freeze
Pop out the frozen cubes and store them in a freezer bag
Label the container with the date
Use frozen basil within 6 to 12 months