Prepare large rose gold baking tray (38 x 26cm) with baking paper. (lightly grease tray and scrunch up paper, then press it in, ensuring it comes just up the sides, but no further)
Place a bowl on the lid of the Thermomix and weigh in flour, baking powder and salt.
Set aside and have a sieve ready.
Insert butterfly and add eggs and sugar to the bowl.
Set machine to 6 min/37/sp 3.5/MC on.
Then set to 6 min/3.5 no heat and no MC.
Sieve flour mix into egg mixture.
Mix 3 sec/sp 3.
Remove butterfly and use spatula to gently stir in any remaining flour.
Pour into tray and bake 14 - 16 minutes.
Meanwhile, lay a tea towel on the bench and place another sheet of baking paper on top - larger than the cake. Sprinkle with the extra caster sugar.
Carefully turn out cooked cake onto baking paper and remove the paper from the top of the cake.
Make a slice 2 cm in from one short edge without cutting all the way through - this makes it easier to roll up.
Roll up, using the tea towel and enclosing the sugared paper.
Cool, then carefully unroll and spread with jam. re-roll without the baking paper.
Slice with a serrated knife.
Freezes well.
Notes
To fill with jam and cream, use the butterfly in a clean bowl to whip thickened cream on speed 4 until very, very stiff. Spread over the jam. Instead of caster sugar, use coconut to coat.
Recipe by ThermoGourmand at https://thermogourmand.com.au/index.php/2022/09/25/jam-sponge-roll/