Mix yogurt with maple syrup and vanilla in small bowl. Chop walnuts. Set aside.

Chop apples and place into a large serving bowl.

Sprinkle apples with a few shakes of cinnamon, to taste.

Pour yogurt mixture onto apples and stir to combine.

Cut up bananas into pieces on top of apples. Add chopped walnuts and grapes, if using, to bowl and stir gently to combine. Serve immediately.