Yes! You can make a sponge cake in the Thermomix. The recipe is one I normally make in my beloved Kitchen Aid. It has never failed for me, even once when I left out one of the raising agents.
When whipping eggs or egg whites in the Thermomix, it's advisable to use a little heat. I whip eggs on 37, but you can even go to 60C.
No Fail Thermomix Sponge
4 large eggs
100g castor sugar (or blitz your sugar in the Thermomix first)
100g wheaten cornflour (also known as wheat starch)
70g custard powder
1 tsp plain flour
1 tsp cream of tartar
1/2 tsp bi-carb soda
Preheat oven to 180 degrees C. Line two 20cm deep sided tins with baking paper. Grease the sides lightly and sprinkle with little cornflour.
Place butterfly into Thermomix bowl.
Add eggs and beat on 37C for 8 minutes on speed 4.
While this is beating, sift flour onto baking paper twice.
Scrape down lid.
Add sugar and beat on speed 4 for 3 minutes.
Add flour and mix on speed 1 - 2 for about 20 seconds.
Pour evenly into tins and bake for 25 minutes. Turn cakes out onto wire rack and remove paper.
Carefully turn over. Allow to cool. Pop one in the freezer and eat the other!
Decorate as desired. For this particular sponge, I used home made Plum & Mulberry Jam in the middle, whipped cream and grated chocolate on top.