Cut the watermelon into cubes and remove all seeds, then add them to your blender. Blend on high speed for 1-2 minutes until you have a smooth juice. I always use fresh watermelon rather than frozen because it creates a naturally creamy texture without over-iciness—the vanilla ice cream will provide all the chill you need.

Add the vanilla ice cream scoops to the watermelon juice in the blender, then add the fresh lime juice and sea salt. Blend on medium-high speed for 1-2 minutes until completely smooth and creamy. The lime juice brightens the sweetness of the watermelon while the salt enhances all the flavors—don't skip it! Stop blending once you reach a thick milkshake consistency; over-blending will make it too thin.

Pour the milkshake into chilled glasses, filling them about three-quarters full. Top each glass with a generous dollop of whipped cream and garnish with a fresh watermelon slice on the rim. Serve immediately with a straw and spoon for the whipped cream topping.