Place the chocolate, cornflour or flour, and tonka bean into the Thermomix bowl and mill 10 sec/speed 10.
Add remaining custard ingredients and cook 8 min/80°C/speed 4. Cook further 3 min/90°C/speed 4. Cool slightly before dividing between serving glasses or bowls equally. Cool to room temperature before proceeding.
When ready to serve, whip the mascarpone and vanilla as you would any cream, using the butterfly. It whips MUCH quicker than cream, so don't get distracted, probably will only take around 6-8 seconds.
Arrange custard, fruit, coulis, mascarpone, more fruit and then just a touch of the reduction in glasses. Top with meringues if using...so cute!