While there are many different varieties of basil, any will do, except Thai Basil. Genovese Basil is one of our favorites use to make a classic pesto recipe. Just be sure to pick over your leaves and remove any that are wilting or have spots. Wash your basil just before you use it in cold water and then dry the leaves well with paper towels. The key to making perfect pesto is using fresh, bright green basil leaves. A good pesto will be bright green.