In a small pot, combine the water and allulose over medium heat. Bring to a boil, allowing the allulose to melt.
After 3-4 minutes, the allulose will start turning yellow. Immediately add the butter and whisk for about 20 seconds.
Pour in the heavy cream and continue whisking while cooking on medium heat for another minute. The mixture will bubble and rise in the pot.
Turn off the heat and stir in the salt. The caramel is now ready to use.
Notes
When using allulose, add the butter as soon as the mixture turns yellow to avoid burning. If substituting with xylitol, wait until it turns golden brown before adding butter.