Simmer away, stirring constantly till the glaze coats your spoon. Remove from heat.
While the glaze is simmering preheat a grill pan over high heat.
Spray the pan with cooking spray.
Sear each side of the watermelon 2-3 minutes per side or until a nice char has formed.
Place each charred piece on a cooling rack with a pan underneath it to catch any drippings.
To assemble place one piece of charred watermelon on the skewer followed by a slice of mozzarella, basil leaf and then repeat ending with a slice of watermelon.
If the glaze has thickened too much, put over low heat to liquefy again.
Drizzle glaze over the skewers.
If there is any glaze left, pour into jar or bottle.