Light and Moist Chocolate Sponge Cake - egg whites

Method

• About the ingredients: I recommend using large eggs.
• Refrigerate until use.
• You can substitute margarine for baking for the butter.
• Preliminaries: Line the mold with parchment paper.
• If the paper curls up, oil the cake tin before putting in the paper and it will stick to the oil.
• Put egg whites in a bowl, and whip with a handheld mixer.
• (Make sure that you use an impeccably clean bowl.
• If it has any water or oil in it, the egg whites won't whip up properly!)
• When the egg whites are whipped to an even, smooth consistency, add 1/2 of the granulated sugar and whip together.
• When it's very fluffy add the rest of the sugar, and keep whipping until it turns into a smooth, shiny meringue.
• If stiff peaks form when you lift the mixer, it's done!
• (It's a must to make a meringue that forms peaks!)
• Add the yolks to the meringue and mix well.
• (When the yolks are evenly incorporated, it's done.)
• Sift the cake flour into the batter.
• Use a rubber spatula and mix up from the bottom using a cut-and-fold motion.
• It's easier if you turn the bowl with one hand as you mix!
• (Whatever you do, don't beat or knead the batter.
• Mix as little as possible.)
• Put the butter and milk into a heatproof bowl, cover with plastic wrap and microwave for a minute and a half.
• (You can also warm it in a small pan.)
• When the butter and milk are warm, sift in the cocoa powder and mix to dissolve.
• (It's a bother, but be sure to sift it!)
• Keep on mixing until the cocoa has completely dissolved!
• (Make sure there are no lumps!)
• Add the Step 9 mix to the Step 6 batter a little at a time.
• (If you add it all at once the cocoa butter will sink down to the bottom!)
• Mix the batter up from the bottom while turning the bowl with one hand, using a cutting motion and working quickly.
• (Be sure not to beat or knead it at this point too.
• Mix as little as possible.)
• Pour the batter into the lined mold.
• (Since the batter at the bottom of the bowl does not rise well, pour it around the perimeter of the mold, where it will cook faster.)
• Drop the filled cake pan 4 to 5 times at a height to eliminate air pockets, and smooth out the surface.
• Bake for 30 to 40 minutes in a preheated 340F/170C oven.
• If you poke the middle with a bamboo skewer and it comes out clean, it's done!
• As soon as it's baked, drop it at a height of 20-30 cm onto a work surface to prevent the cake from shrinking.
• Put a well wrung out moistened kitchen towel on your work surface, and take the spongecake out of the cake pan.
• Peel the paper off the sides.
• (Put the cake top upside down.)
• Put the cake pan back on the cake and leave for 2 to 3 minutes.
• (This is to make the top surface flat, and to even out the moisture in the cake.)
• Take the cake pan off and peel off the paper from the bottom.
• Turn the cake over and cool on a cake rack.
• Cover the spongecake with a moistened and tightly wrung out kitchen towel, and leave to cool.
• When the spongecake is cool, slice horizontally and fill and decorate as you like.
• (The cake is easier to slice if you let it rest for a day.
• Keep in a plastic bag.)
• How to slice the sponge cake cleanly: Mark the sides vertically with a knife so that you can re-stack the layers later.
• If you don't have a cake slicer: Insert toothpicks where you want to slice through the cake, starting with the upper layer, spacing the toothpicks evenly (in 4 to 8 places).
• Slice through the cake on top of the toothpicks horizontally.
• Slice the lower layer in the same way.
• Re-stack the layers, following the vertical marks you made in Step 19.
• Tip: If you flip the bottom layer over, put the middle layer on top, and the top layer in the middle, the cake will be easier to decorate.
• To make a 12 cm diameter cake: Re-calculate the amounts based on 1 egg.
• (I halve the amounts mixed for the 18 cm cake.)
• Bake for 25 to 30 minutes (28 minutes works best for my oven).
• To make a 15 cm diameter cake: Halve the amount of ingredients used for the 20 cm cake.
• Bake for 30 to 35 minutes (340F/170C, 34 minutes in a gas oven).
• To make a 21 cm diameter cake: Re-calculate the amounts based on 5 eggs (Or multiply the amounts for the 18 cm cake by 1.5.)
• Bake for 30 to 40 minutes (35 minutes works best).
• To make a 12 cm diameter cake plus a 15 cm diameter cake: Use the amount of ingredients specified for the 18 cm or 20 cm cakes (I prefer the latter).
• Baking times - 12 cm = 28 minutes, 15 cm = 34 minutes.
• When trying to figure out how much batter you need for a particular round or square mold, just keep in mind that you should have 1 egg for every 500 ml of batter poured inside the pan.