Kue Lapis (Indonesian steamed rainbow layer cake)

Method

1. Set up a wok or a large, wide pot as a steamer: place a rack or trivet inside, add water to come about 4 cm up the sides without touching the rack, and bring it to a rolling boil, then reduce to a steady simmer. Lightly oil a 20 cm square heatproof dish with the neutral oil and set it in the steamer to preheat, empty, for about 5 minutes while you make the batter.
2. In a large bowl, whisk together the tapioca starch, rice flour, sugar, and salt. Pour in the coconut milk in a steady stream, whisking until completely smooth with no lumps.
3. Whisking constantly, pour in the boiling water in a thin stream; this partially cooks the starches and is what gives kue lapis its chewy, not gluey, bite. Whisk in the vanilla extract if using, then strain the whole batter through a fine sieve into a large jug to catch any lumps.
4. Divide the batter evenly into three bowls, about 300 ml each. Leave one bowl plain. Stir the pandan extract into the second until evenly green. Stir the beetroot powder into the third until evenly pink, dissolving it in a teaspoon of water first if it is a powder.
5. Ladle about 100 ml of one color into the hot, oiled dish and spread it into an even layer. Cover and steam for 7 to 8 minutes, until the layer looks matte and fully set rather than wet and glossy.
6. Uncover briefly and blot any condensation pooled on the surface with a clean paper towel. Ladle in about 100 ml of the next color and spread it evenly. Cover and steam for 5 to 6 minutes, until matte and set, then repeat with the third color.
7. Keep alternating the three colors in the same order, blotting condensation and steaming each new layer for 5 to 6 minutes, until all the batter is used; you should end up with about 9 thin layers. Steam the final layer for 10 minutes, to make sure it and the layers beneath are fully cooked through.
8. Lift the dish out of the steamer and let the cake cool completely, uncovered, at room temperature; this takes at least 4 hours, and it firms up further and cuts more cleanly if left overnight. Do not refrigerate to speed this up, or the layers turn rubbery.
9. Run a thin knife around the edge and turn the cake out onto a board. Slice with an oiled knife, wiping and re-oiling it between cuts, into about 12 small pieces, or serve it the way it is traditionally eaten, peeled apart by hand, layer by layer.

Notes

• This is a genuinely time-intensive dessert. Budget about an hour and a half of hands-on prep and steaming, then a separate block of at least 4 hours, ideally overnight, for the cake to firm up before you cut it; do not try to rush either half.
• For a full six-color rainbow, divide the batter into six portions instead of three (about 150 ml each) and tint each a different shade: try turmeric or a drop of yellow for gold, a little more beetroot for red, extra pandan for a deeper green, and butterfly pea powder for blue, alongside the plain and pink layers. Pour thinner, roughly 60 ml layers, steaming each for about 4 minutes, and expect 40 to 50 minutes more active steaming time than the three-color version here.
• Gel-based food colorings dissolve into the batter more evenly than liquid drops; oil-based colors tend to separate and streak. Rose syrup is a traditional alternative to beetroot for the pink layers, though it adds its own sweetness and floral flavor.
• Store leftover cake in an airtight container at room temperature for up to 2 days, or refrigerate for up to 5 days. The layers stiffen when cold, so bring pieces back to room temperature, or steam them for 2 to 3 minutes, before serving. This cake does not freeze well; the layers turn grainy and separate when thawed.
• Check that your tapioca starch, rice flour, and any food colorings are certified gluten-free if that matters for your household, since cross-contact during milling is possible even though none of the core ingredients contain wheat.

Sources Consulted

• Simone’s Kitchen, “Kue Lapis Recipe”
• Beautiful Voyager, “Kue Lapis (Steamed Layer Cake)”
• What To Cook Today, “Gao Teng Kueh / Jiu Ceng Gao / Steamed Kue Lapis”
• Indonesia Flour, “Kue Lapis, Layer Cake”