preheat oven to 180 C (355 F) and line a slice tin with baking paper.
Place grapes, bananas and vanilla into a blender or food processor and blend until smooth.
Pour fruit mixture into a mixing bowl.
Lightly whisk eggs and add to mixing bowl, whisk to combine.
Add flours and mix until smooth.
Pour mixture into prepared slice tin and use a spoon or spatula to spread it out evenly.
Bake for 20 - 25 minutes or until a knife inserted into the centre comes out clean.
Allow to cool for 10 mins before serving, allow to cool completely before storing in an airtight container in the fridge.
Freezes well.