Combine the custard ingredients in a blender and blend until smooth. Pour into two greased 6-oz ramekins or bowls. Preheat the oven to 325F. Place the ramekins into a baking dish and place in the oven. Pour hot water into the baking dish until halfway up the sides of the ramekins. Bake for 30 minutes or until set. Remove and chill for at least an hour before serving.
To make the sauce, melt the butter, sweetener, and the caramel extract in the microwave for 30 seconds (or in a saucepan on the stove until melted). Whisk together until fully blended. Divide between and pour over the two custards just before serving.
Serves 2