Break the dark chocolate into small pieces.
Add dark chocolate, allulose powder, and low-fat milk to a microwave-safe bowl.
Microwave for 30 seconds at a time, stirring well between intervals until melted.
Mix thoroughly and add vanilla extract.
Pour the fudge mixture into a mold lined with baking paper.
Refrigerate for at least 2 hours to set.
Cut into bite-sized pieces.