In a square baking dish, grease using the butter.
Then dredge the tray in flour and place in the fridge for 15-20 minutes.
Meanwhile, preheat the oven to 200 degrees Celsius fan.
Prepare the watermelon by cutting it into chunks and removing the seeds.
Add the watermelon chunks to a bowl along with the flour and sugar.
Mix with your hands to combine until all the watermelon is evenly coated.
Take out the pregreased dish from the fridge, pour the watermelon batter and spread out evenly.
Top with the olive oil, cinnamon and sesame seeds.
Bake for one hour, reducing the temperature to 180 degrees Celsius fan half way through.
Serve warm or cold, and store in the fridge for up to 3 days.
