Melt the butter in a medium-sized heavy-bottomed saucepan over medium heat. Stir in the allulose and bring to a low simmer. While gently whisking, slowly pour in the cream. Continue cooking, stirring constantly, until the caramel starts to thicken and turn golden brown.
Remove the caramel from the heat and stir in the vanilla and salt.
Allow to cool for 10 minutes before transferring to a heat-proof container with a lid. The caramel will continue to thicken as it cools. Do not cover the container until the caramel sauce has completely cooled.
Notes
Allulose is the best sweetener for this recipe because it keeps the caramel smooth and does not crystallize when cooled.Store in a jar in the refrigerator. When ready to use, reheat in a saucepan over low heat.