Preheat oven to 200ºC and butter each ramekin very well. Dust generously with cocoa. Set ramekins aside on a baking tray.
Place sugar into Thermomix bowl and mill 10 sec/speed 10.
Add butter and blend 10 sec/speed 4.
Add vanilla, eggs, salt and flour. Blend 10 sec/speed 5.
Add melted chocolate that has been slightly cooled. (I used microwave, but induction cooktop is excellent for melting chocolate as well. It can be done in your Thermomix, but it is quite slow and you would need to do this process first.)
Blend 10 sec/speed 4. Scrape down sides of bowl and repeat.
Divide mixture between the prepared ramekins. Push a truffle (without any nuts or other coating FYI) into the centre of each and cover with pudding batter.
Bake 10-12 minutes until still springy to touch.
Use a knife to loosen outer edges of cake and turn upside down to serve. These must be served immediately unless reserving for later, as the centre needs to be molten.
Serve with cream, mascarpone or ice cream to taste. Dust with additional cocoa or icing sugar if desired. You can refrigerate these fully assembled, but uncooked until ready to serve. It is best to eat them hot, straight from the oven. They may take a little longer if being cooked straight from the fridge. Garnish with berries of choice.