Blend watermelon into a puree using a blender or stick mixer.
Whisk egg and watermelon together in a bowl.
Add flour and mix to combine.
Heat a little butter or olive oil in a frying pan on medium heat.
Drop spoonfuls of the pancake mixture into the pan to form little round pancakes.
Cook until craters are beginning to form in the top of the pancakes and the bottom has turned golden brown.
Flip pancakes over and cook until the other side is golden brown as well.
Can be served warm or cold.
If not eating immediately, cool the pancakes to room temperature and them store them in the fridge in an airtight container for a few days.
To freeze, wrap cooled pancakes in plastic wrap then store in a freezer bag/container.