Place chocolate into the Thermomix bowl and grate for 10 seconds on Speed 6.
Add 50 grams of the cream and melt together for 4 minutes, 50 degrees, Speed 2.
Add the egg yolks and mix for 15 seconds, Speed 4.
Pour the mixture into a separate bowl and set aside.
Clean and dry the Thermomix bowl.
Place the butterfly into the Thermomix bowl and whip the remaining 150 grams of full fat cream on Speed 4 until it has thickened (this will take about 10-30 seconds).
Place the whipped cream into a separate bowl.
Clean and dry the Thermomix bowl - make sure it's very dry or otherwise your egg whites won't whip in the next step!
Place the butterfly into the Thermomix bowl and add the egg whites, caster sugar and a pinch of salt (the salt will stabilise the egg whites).
Whip for 3 and ½ minutes on Speed 3.5 or until stiff peaks have formed.
Add the chocolate mixture and the whipped cream to the Thermomix bowl.
Combine everything together for 20 seconds on Reverse Speed 3.
If the mixture isn't completely combined, finish mixing it with the spatula.
Divide amongst your serving bowls and refrigerate for 2 - 3 hours.