Place watermelon round on serving plate. Scrape yogourt into small re-sealable plastic bag and snip off corner. Drizzle Greek yogourt over watermelon.
Sprinkle with feta cheese and mint. Drizzle with honey. Cut into quarters to serve.
For larger “pizza,” double the topping quantities and use 12-in. (30-cm) diameter round watermelon slice. For a sweet version, top with vanilla yogourt, flaked coconut, lime zest and raspberries.