In a small saucepan, bring the sugar and water to a boil over medium-high heat. Simmer, stirring occasionally, until the sugar has dissolved, about 5 minutes. Cool for 20 minutes.
Pour the cooled syrup into a blender. Add the yogurt, orange juice, bananas, orange zest, vanilla extract, and ice. Blend until the mixture is smooth. Pour into glasses and serve.
Recipe courtesy of Giada De Laurentiis