Add the watermelon to a blender and blend until smooth.
Pour through a fine mesh strainer over a bowl. Let some of the liquid drain through for about 5–10 seconds, then pour the remaining watermelon pulp from the strainer into a saucepan.
Add the lemon juice and honey, if using.
Heat over medium heat until it reaches a light simmer. Do not let it come to a full boil.
Whisk in the gelatin and continue stirring until completely dissolved.
Remove from the heat and pour into silicone molds, a parchment-lined 8x8 pan, or a muffin tin.
Refrigerate until set.
Enjoy as-is or cut into squares if using a pan.
Store in the refrigerator and enjoy all week long!
