Heat up half the cup of water in a mixing bowl until the water is quite is hot. Pour in the two envelopes of unflavored gelatin and mix well. Stir in the other half cup of water and allow to cool. You don't want the liquid to cool so much that it starts firming up, but you don't want to add the alcohol to the mixture while it's hot.

Mix in the ½ teaspoon of coconut extract, and ? cup of powdered erythritol. Check the taste and add more erythritol if you think you will need it.

Stir in the rum.

Pour the liquid into the containers you want to use. Place in the fridge for about an hour and allow to firm up.

You can serve these plain, or with a dollop of fresh whipped cream.