Makes one 30cm x 25cm sheet cake, roll up into approx. 20cm long roll
55g plain flour
40ml coconut milk *
1 whole egg
3 egg yolks
few drops purple food colouring, or taro essence if available (optional)
3 egg whites
1/4 teaspoon salt
80g caster sugar
300g taro paste filling
* I used Kara brand Classic UHT Natural Coconut Milk.
1. Preheat oven to 180°C. Grease a 30cm x 25cm Swiss roll tin and line the base with baking paper.
2. Melt butter over gentle heat and bring to just simmering. Remove from heat and add flour all at once, whisk quickly to form a thick roux. Add coconut milk and whisk to combine.
3. Add whole egg and whisk until smooth. Add egg yolk one at a time and whisk in well after each addition. Mix in food colouring to a light purple hue. Transfer the mixture to a large mixing bowl, set aside.
4. In another mixing bowl, beat egg whites and salt until foamy. Gradually add sugar, one tablespoon at a time, and beat until just under stiff peaks stage.
5. Fold 1/3 of the egg white mixture into the yolk mixture. Repeat two more times with the remaining egg white mixture.
6. Pour the sponge batter into the prepared tin. Smooth the surface and give the tin a gentle tap on the bench to settle the batter.
7. Bake for about 20 minutes, or until the cake feels springy when touched lightly.
8. Remove from oven and loosen the sides of the cake from the tin. Turn out onto a tea towel immediately. Remove lining paper. Turn cake right side up (brown side on top) and let cake cool completely this way on the tea towel, about 20-30 minutes or until room temperature. Do not let it cool too long or the cake will lose too much moisture and crack when rolling up.
9. Cut away the hard edges from the cake. Spread taro paste filling onto the cake (on the brown side). Roll up from the short side; roll as tightly as possible. A good way to roll up the cake is by placing a rolling pin at the end where you are going to start rolling (with the sheet cake still sitting on the tea towel). Fold the end of the tea towel over the rolling pin to wrap it up. Then start rolling the rolling pin forward (as you roll more of the tea towel will wrap over the pin), at the same time start rolling up the cake in front of the rolling pin. Keep rolling the pin forward until the cake if fully rolled up. Then release the rolling pin from the tea towel and now wrap the tea towel over the cake roll and leave it until the cake roll is stable before cutting and serving.
Taste: Spongy, moist and soft cake roll with sweet and aromatic taro paste filling
Consume: Best within 2-3 days
Storage: Store in airtight container in the refrigerator
Recipe Reference(s): ‘Japanese Cotton Sponge Cake’ by Alex Goh