The next important step is the baking of the sponge. You should bake it just until the toothpick inserted comes out clean. A minute more than that and you will, although still have a beautiful soft and moist sponge, get cracks while rolling it with the filling. While I failed to understand this in my first attempt and hence got a few cracks here and there, it is definitely a lesson well learnt. I also tried to decorate the swiss roll with a baked pattern but I guess I have to read up a little more to get hold of the technique. My pattern got a bit burnt and so I had to invert the swiss roll and add the filling on the side of the pattern, hence those red starwberry spots in between the chocolate filling. So keeping the decorated Swiss Roll for another day!
4 large eggs separated (it is best to separate eggs when they are fresh and cold out of the refrigerator; once separated, bring them to room temperature before starting the procedure)
1/4 tsp salt
A pinch of cream of tartar (optional)
3/4 cup castor sugar
3/4 cup all purpose flour
1 tsp baking powder
1 tsp vanila extract
For the filling
4 cups icing sugar
1/3 cup unsweetened cocoa powder
3 tbsp butter (preferably unsalted) cut into squares
120 ml milk at room temperature
P.S.: This is a standard chocolate sauce recipe. The excess sauce you can store in the fridge for later use. You can also use any filling as you wish like fresh fruit jam, whipped cream, etc.
Take a 32x23 cm flat baking dish and grease it. Line the dish with parchment paper in a way that there are no bubbles or raised edges. It should be as smooth as possible. This will help you get a smooth wrinkle-free base once baked. The greasing of the bottom of the pan before lining helps keep the parchment paper in place.
Meanwhile, start pre-heating the oven at 180 degree celsius for 10 minutes.
Now add the egg whites and with the help of a spatula (never use an electric beater) fold into the mixture till smooth. Take care not to overmix the batter which will deflate the whites. Also, always move the spoon in one direction to fold in the whites. Pour this batter into the prepared baking dish and smooth out the top.
Bake in the pre-heated oven for 15-20 minutes or until a toothpick inserted comes out clean. Check at 15 minutes and then again in 2-3 minutes. A minute over baked and you are sure to get cracks on top while rolling as well as hard edges.