In a medium heatproof bowl, pour the contents of the sugar-free gelatin mix. Carefully add the boiling water.
Whisk vigorously for at least 2 minutes, or until the gelatin powder is completely dissolved. Ensure there are no granules left at the bottom.
If using unflavored protein powder, gradually whisk it into the dissolved gelatin mixture until smooth and well combined. This may take a minute or two to fully incorporate without clumps.
Stir in the cold water and any optional sugar-free flavoring extracts. Continue whisking until everything is thoroughly blended.
Pour the mixture into individual serving bowls, cups, or a small dish.
Refrigerate for at least 2-4 hours, or until firm and set. The time may vary depending on your refrigerator and the size of your serving dishes.