Use a chef's knife or mandoline slicer to cut the watermelon into thin, even slices, approximately 1/8-inch thick. Arrange the slices on a large baking sheet or platter, patting them dry with paper towels to remove excess moisture.
Stack the watermelon slices in layers on a serving plate or cake stand, starting from the center and working outward in concentric circles. Slightly overlap the slices to create the appearance of a layered cake. Refrigerate for 10 minutes to help the slices adhere slightly and firm up.
Chop the fresh basil leaves finely and sprinkle evenly over the top of the layered watermelon stack, ensuring coverage for flavor and visual appeal.
Lightly drizzle honey over the entire watermelon cake using a basting brush or spoon, focusing on the edges and top to create a shiny, sweet glaze. Adjust the amount to taste.
Place the finished watermelon cake in the refrigerator for an additional 5-10 minutes to set the honey glaze. Remove from the fridge and serve immediately, optionally garnished with additional basil leaves.
