Whip cream - To a large mixing bowl, add the cream and vanilla extract and whip to stiff peaks using an electric hand mixer.
Add egg yolks - Add the egg yolks to the cream mixture and fold through using a spatula.
Gently melt butter and chocolate - To a heatproof bowl, add the chocolate and butter and microwave for 10 seconds at a time, stirring each time until melted and smooth.
Whip chocolate and cream - Add the warm chocolate mixture to the cream mixture and mix in using the electric hand mixer.
Whip egg whites - Add the egg whites and sugar to a separate bowl. Use clean beaters to whip to stiff peaks.
Gently combine everything - Add the meringue to the chocolate cream mixture and fold through using a spatula until well combined.
To finish - Pour the mixture into your serving cups. Allow to set overnight. Serve with a dollop of crème fraiche and some chocolate shavings.
Notes
Eggs - Use large eggs (55g each) for this recipe. They’re easier to divide when cold, but should be at room temperature before whipping for the best texture. If raw eggs aren’t safe to consume in your country, use pasteurized eggs instead.Why did my chocolate and butter seize? When microwaving chocolate and butter, it’s best to do it slowly. Otherwise, it will seize if overheated. If you want a safe option, melt it over a double boiler.Mixing the chocolate into the cream mixture - To avoid the chocolate solidifying in the cream mixture, add the chocolate mixture into it while it’s slightly warm. And use an electric hand mixer to mix it in. Folding it through using a spatula can also result in little bits of solidified chocolate.Storage - This Chocolate Mousse can be stored in the fridge for up to one day.Chocolate - Cooking chocolate is best for this recipe because it melts more smoothly than regular chocolate. Melting it with butter at the start ensures it has time to cool to room temperature before use. Avoid chilling it in the fridge to speed up cooling, as this will cause it to harden and require re-melting.No Microwave? No Problem! Melt chocolate using a double boiler. Fill a medium saucepan with water (about 1/4 full) and bring to a gentle boil. Place a heatproof bowl on top, ensuring it doesn’t touch the water. Add the chocolate and butter, stirring occasionally until smooth and fully melted.How to Pasteurize Eggs - Place eggs in a large saucepan and cover them with water. Heat to 140°F (60°C), using a thermometer to monitor the temperature. Hold at 140°F (60°C) for 3 minutes, then remove and rinse with cold water to cool. Store in the fridge until needed. This process reduces bacteria, making raw eggs safer to consume.