Step 1: Preheat your oven to 325°F (163°C).
Step 2: In a saucepan over medium heat, combine the heavy cream and vanilla extract. Heat until just simmering, then remove from heat and allow to cool slightly.
Step 3: In a mixing bowl, whisk the egg yolks and allulose together until pale and slightly thickened.
Step 4: Gradually pour the warm cream mixture into the egg yolk mixture while whisking continuously.
Step 5: Strain the custard through a fine-mesh sieve into a clean bowl or measuring cup.
Step 6: Place your ramekins in a baking dish. Pour the custard into the ramekins, filling them about ¾ full. Add hot water to the baking dish.
Step 7: Bake for 30-35 minutes, or until set but slightly jiggly in the center. Let cool.
Step 8: Transfer the ramekins to the refrigerator and chill for at least 2 hours.
Step 9: Before serving, sprinkle allulose on top and caramelize using a kitchen torch.
Step 10: Serve immediately and enjoy!