You can substitute commercial yogurt starter for the Greek yogurt according to the package directions.
For a thicker, creamier yogurt, transfer chilled yogurt to a strainer lined with two layers of 100%-cotton cheesecloth or a clean coffee filter set over a bowl. Cover and chill 3 to 4 hours more or until yogurt reaches desired consistency.
Prepare as directed, except stir 1/2 to 1 Tbsp. honey or sugar (if desired) and 3/4 tsp. vanilla into each container before serving.Per serving: same as above.