I always start by rinsing the watermelon under cool water and drying it completely, since any dirt on the rind can transfer to your knife. Next, I slice a thin piece off the bottom so it sits flat and doesn't wobble while I'm carving. I set it on my cutting board stem-side up and take a moment to study its natural shape.
Using my chef's knife, I cut a circle around the top of the watermelon, angling the blade slightly inward like a cone so the lid doesn't fall straight through later. I lift the top off carefully and set it aside. This opening is what lets me scoop out the flesh and eventually see inside the finished skull.
With my large spoon, I scoop out as much of the red flesh as I can reach, keeping the rind wall about three-quarters of an inch thick for stability. I save every bit of scooped fruit in a bowl, since it becomes the melon balls I serve alongside the finished carving later.
This is the step I never skip. I use a dry-erase marker to trace the eye sockets, nose cavity, and jagged teeth directly onto the watermelon's surface, using a printed stencil if I have one handy. Sketching first means I'm not guessing with a sharp knife, which saves a lot of frustration.
I start with the eye sockets, carving two triangle or oval shapes using my paring knife, pressing straight down and then angling in to pop out the section. I move to the nose next, then work slowly along the jagged tooth line across the bottom, cutting small triangular notches to mimic real teeth.
Once the main features are cut, I go back over every socket and notch with my paring knife to trim away any leftover green skin, which makes the white rind underneath stand out sharply. This extra five minutes is what gives the skull that crisp, defined look you see in photos.
I spoon my reserved melon balls back inside the hollowed skull, letting a few spill out the mouth or eye sockets for a dramatic, "overflowing" effect. I pop the whole thing in the fridge for about 30 minutes before serving so everything stays cold and crisp for guests