1. Lightly grease or line an 8×8-inch dish so the jello slices lift out more easily after chilling.

2. In a bowl, dissolve the lime gelatin in 1 cup boiling water, then stir in 1/2 cup cold water.

3. Let the mixture cool slightly, pour it into the prepared dish, and refrigerate until mostly firm.

4. In a separate bowl, sprinkle the unflavored gelatin over 1/4 cup cold water and let it bloom for 1 minute.

5. Add 1/2 cup boiling water and stir until fully dissolved, then whisk in the sweetened condensed milk until smooth.

6. Cool the creamy mixture to room temperature, gently pour it over the green layer, and refrigerate until firm.

7. In another bowl, dissolve the cherry gelatin in 1 cup boiling water, then stir in 1/2 cup cold water.

8. Cool slightly, carefully pour over the white layer, and refrigerate until completely set.

9. Slice into squares, top with whipped topping, and finish with lime zest before serving.