Melt the chocolate.
Break the chocolate into small pieces and melt gently using a double boiler or microwave (15-second intervals). Stir until smooth. Let cool slightly.
Whip the cream.
In a chilled bowl, beat ¾ cup of the cream until soft peaks form. Place in the fridge.
Prepare the eggs.
In another bowl, whisk egg yolks, vanilla, and erythritol until pale and slightly thickened.
Combine.
Slowly whisk the melted chocolate into the yolk mixture. Add a spoonful of whipped cream to loosen it, then gently fold in the rest until smooth and airy.
Whip egg whites.
In a clean bowl, beat the egg whites with a pinch of salt until stiff peaks form. Fold gently into the chocolate mixture to keep the mousse light.
Chill.
Spoon into glasses or ramekins and refrigerate for at least 2 hours.
Make the “blood.”
In a small saucepan, simmer raspberries, water, erythritol, and lemon juice for 5 minutes. Strain to remove seeds if desired. Let cool completely.
Assemble.
Drizzle the raspberry sauce over each mousse so it looks like dripping blood. Add a few raspberries and a sprinkle of dark chocolate on top.