Line a 9x5 inch loaf pan with foil, smoothing out wrinkles as much as possible.
Set a heatproof bowl over a pan of barely simmering water. Do not allow the bottom of the bowl to touch the water. Add butter, chocolate and sweetener and whisk until melted and smooth.
Stir in eggs until well combined. Mixture will seize; this is normal. Whisk in the coffee or water until mixture smooths out again.
Pour into prepared pan and spread to the edges, smoothing top as much as possible. Refrigerate at least 4 hours and up to overnight.
Combine cranberries water and sweetener in a medium saucepan over medium heat. Cook until berries pop, 5 to 10 minutes.
Transfer to a blender or food processor and puree until completely smooth.
Slice terrine and serve with a drizzle of coulis and lightly sweetened whipped cream.
Serves 10. Each serving has 6.45 g of carbs and 3.28 g of fiber. Total NET CARBS = 3.17 g.Food energy: 246kcal Saturated fatty acids: 14.88g Total fat: 23.11g Calories from fat: 207 Cholesterol: 111mg Carbohydrate: 6.45g Total dietary fiber: 3.28g Protein: 4.89g Sodium: 154mg