Soak the 3 sheets of gelatin in cold water for about 10 minutes

Bring water and mint to a boil and let it boil for 10 minutes, turn off the heat and let the mint steep in the water for a few minutes.

Pour sugar, gelatin, and fruit coloring into a bowl.

Strain the mint, pour the liquid over the sugar, gelatin, and fruit coloring and stir until the sugar and gelatin are dissolved. Let the liquid cool on the kitchen counter for about 2 hours before pouring it over the cake.

Let the cake sit in the fridge overnight so the jelly can set.