While chocolate layer is setting, make the two green layers. Pour 1 1/4 cup of water into a small saucepan and sprinkle with 2 packets unflavored gelatin and allow to soak in a minute or two. Turn on the burner and heat over medium, stirring constantly, until gelatin dissolves. Add 1-2 tablespoons of sugar and stir until it dissolves (sugar is optional, but it helps mellow the mint a bit). Remove from heat and stir in 1/2 cup of crème de menthe.