1. Preheat oven to 180C on conventional mode (top and bottom heat). Line the base and sides of a 20 cm square cake pan, at least 5 cm deep, with a large square of wilted banana leaf (no need to grease), shiny side up, tucking its corners to fit.
2. In a muslin cloth or bag, squeeze tapioca a handful at a time to extract as much juice as possible – you should get around 230 g to 280 g juice. If you get less than 230g juice, add an extra 40g water to the juice. Set tapioca pulp aside.
3. Combine tapioca juice with coconut milk, sugar, salt, butter and egg yolks in a heavy-bottomed pan. Set over medium-low heat and stir constantly, scraping pan base and sides with a whisk, until mixture thickens into a creamy but pourable custard. Scrape into a bowl, add tapioca pulp and mix very well until batter is even and lump-free.
4. Scrape batter into lined pan. Bake on the oven’s lowest shelf for 40 to 45 minutes. Then, scatter cold butter bits over the bengka, and move pan to a high shelf in the upper third of the oven. Bake for 10 to 15 minutes more, until bengka is well browned and a skewer inserted into its centre emerges sticky but clean, with no raw batter on it.
5. Let kueh cool to at least lukewarm before unmoulding. Slice with a plastic knife to serve. Leftovers will keep for 2 to 3 days in the fridge, but will firm up as they age: steam or microwave to warm and soften them before serving.
'The Way Of Kueh' by Christopher Tan ($51.25) is available at all major bookstores.
Photos: Chris Tan & Florence Fong