Place the cherry-flavored gelatin powder in a mixing bowl, ready for mixing.
Pour the hot water over the gelatin powder and whisk vigorously until the powder is completely dissolved and the mixture is clear.
Add the cold citrus juice and cold water to the hot gelatin mixture, stirring gently to combine. The mixture will start to thicken slightly and turn vibrant red.
Pour the gelatin mixture into a skull or brain-shaped mold, filling it about halfway to create layers that resemble brain tissue.
Place the mold in the refrigerator and chill until the gelatin is firm, about 1 to 2 hours.
Remove the mold from the fridge and gently pour a second layer of gelatin over the first, adding more of the mixture to build up a thicker brain-like structure.
Return the mold to the refrigerator and chill again until fully set, about another 2 hours or overnight for best results.
Once set, gently loosen the edges of the gelatin from the mold with a butter knife and carefully invert onto a serving plate.
Carefully lift the mold away, revealing the creepy, brain-like gelatin structure with textured ridges and folds.
Optionally, garnish with edible eyes, red syrup, or additional citrus slices for a more gruesome effect.
Serve chilled and enjoy the spooky, jiggly, brain-like dessert that's perfect for Halloween celebrations.
