Kue Lapis Surabaya - Surabaya Layer Cake

Warning: this wonderfully light and airy chocolate and vanilla layer sponge cake is extremely moreish.  Kue lapis Surabaya is a classic Indonesian cake and even though it is old-fashioned, its simplicity makes this cake... timeless.  The name Surabaya refers to the capital city of East Java.  Funny thing, the name "lapis Surabaya" is only known by the people from outside of the city.  In Surabaya itself, the cake is known by the name of  "spiku".

Classic lapis Surabaya consists of three layers of sponge cakes.  A chocolate sponge sandwiched between two layers of vanilla or plain yellow sponge; or the other way round, a vanilla sponge sandwiched between two layers of chocolate sponge as I have done here.  The layers of cake are glued using strawberry jam. Chopped nuts may be added to the layers for texture for variations, but I'm keeping it simple this time.

Looking at the list of ingredients, yes, there are a lot of egg yolks used here (you can save the whites for meringues or pavlovas, etc) and that what makes the cake so rich.  This makes quite a big cake, perfect for sharing... I managed to get around 40 generous slices.

The addition of instant espresso to the chocolate sponge batter is my own take.  However un-traditional, I think it brings out more of the chocolate flavour.  So, purists out there, please don't sue me.

Kue Lapis Surabaya

For the chocolate sponge:
15 egg yolks
180 gr caster sugar
pinch of salt
50 gr plain flour
25 gr cocoa powder
1 tsp instant espresso
2 tbsp milk powder
180 gr butter

For the vanilla sponge:
8 egg yolks
100 gr caster sugar
pinch of salt
1 tsp vanilla paste, or the seeds from 1 vanilla pod
30 gr plain flour
10 gr corn flour
1 tbsp milk powder
100 gr butter

150 gr strawberry jam

Preheat the oven to 180 C and grease and line a 25 cm square tin.

Using a freestanding or a hand-mixer, whisk 280 gr of butter until pale and fluffy, then divide the butter for the sponges and set aside.

To make the chocolate sponge, whisk the egg yolks with caster sugar and a pinch of salt until thick, light and forms a ribbon.  In a bowl, sieve the flour, cocoa powder, instant espresso and milk powder.  Then slowly add the dry ingredients to the yolks.  Fold in the whipped butter.  Pour the batter into the tin and bake for 25 minutes or until a skewer inserted into the middle of the cake comes out clean.  Remove the cake from the oven, let it cool slightly before removing from the tin to cool completely. Repeat the process to make the vanilla sponge. 

When the chocolate sponge has cooled, cut it in half horizontally using a serrated knife.  Try your best to make sure the layers are even. Spread one half of the cake with half of the strawberry jam. Then top with the vanilla sponge.  Spread the rest of the jam and top with the chocolate sponge.  Cut into slices and you know what to do next...