Pour the sponge cake dough into the 15 cm in diameter cake pan. Bake in 160°C oven for 20 minutes. This is just a guide, so use a bamboo skewer, stick it through the sponge cake and if it comes out clean, then it is ready. Let it cool. When the sponge cake has cooled down, slice into 2 halves about 1.5 cm thick. You can freeze the remaining sponge.