Make sure your basil is washed and completely dry. I wash the entire plant and dry mine overnight on a towel.
Preheat oven to 170 degrees. If your oven’s lowest temperature is 175 or 180, that’s fine.
Place basil leaves on a baking sheet, making sure the leaves don’t overlap. Depending on the amount of basil you have, you might need a few baking sheets.
Bake for 45 minutes to 1 hour, or until basil leaves are dried and can easily crumble. Mine took 50 minutes.
Remove basil from oven and crumble in bowl. The basil should easily crumble upon touching. I like to fill the bowl up with as many basil leaves I can fit in and then crumble with my fingers. You could also use a mortar and pestle.
Store dried basil in jar for storage. I like to reuse spice jars I get from the store. If properly stored dried basil will last 1-2 years.