Khanom Chan — Thai nine-layer pandan and coconut cake

i. Origin & history

Khanom chan is one of the classic Thai sweets, part of the long tradition of khanom Thai refined in the courts and households of the Ayutthaya and early Rattanakosin (Bangkok) periods. Steamed starch-and-coconut cakes are common across Southeast Asia, but the Thai version stands out for its careful layering, its delicate perfumes and its symbolic weight in Thai culture.

The symbolism is central. Chan means a layer, but also a level or rank, and the cake's stacked layers are read as a wish to rise step by step in life — in work, in status, in fortune. Nine is the traditional number of layers because the Thai word for nine, kao (เก้า), sounds like kao (ก้าว), meaning to step forward or progress. Together, nine layers of khanom chan express the hope of continual advancement, and the cake is given at promotions, housewarmings and new ventures as well as weddings.

This makes khanom chan one of the auspicious sweets (khanom mongkhon) served at important ceremonies, alongside the golden egg-yolk sweets thong yip, thong yot and foi thong. Lists of the 'nine auspicious Thai desserts' vary, but khanom chan appears in most of them. Older recipes perfume the coconut milk with jasmine-flower water and smoke the finished cake with a scented candle (tian op), a refinement still used by traditional makers.

Khanom chan is often compared with Indonesian kue lapis, Malaysian kuih lapis, Filipino sapin-sapin and Vietnamese bánh da lợn. All are steamed layer cakes, but Thai khanom chan uses a higher proportion of tapioca starch, giving a chewier, glossier and more elastic texture, and its colours are traditionally limited to the natural green of pandan and the white of coconut, or the blue of butterfly pea flower.

ii. What the tapioca does

The texture of khanom chan comes from the balance of starches. Tapioca starch makes up the majority and gives the cake its chewy, elastic, translucent quality; it is what lets the layers peel apart in clean, stretchy sheets. A smaller amount of rice flour adds body and makes the cake slightly softer and more opaque. Many Thai recipes also include a little mung bean flour or arrowroot, which gives a smoother, silkier set.

The batter is steamed in thin layers so that each sets before the next is added. The starch gelatinises in the steam, turning from cloudy to glossy and translucent. A thin layer sets in about 5 minutes; it should be set but slightly tacky, so the next layer bonds. If the surface is overcooked and dry, the layers separate when cut; if undercooked, the colours bleed together.

The starch settles quickly, so the batter must be stirred before each pour. Using the same small ladle or measure for every layer keeps the thickness even, which is essential to the cake's appearance.

Pandan gives both colour and aroma. Fresh pandan leaves, blended with a little water and squeezed, give a natural, fragrant green juice; the colour is softer than artificial colouring, and the aroma — somewhere between vanilla, rice and fresh grass — is the defining flavour of the cake. The final, top layer is usually the darker colour, and it should be steamed longer to set the whole cake.

iii. Ingredients

Makes 16 servings · scroll the side panel to adjust

• 200 g tapioca starch
• 50 g rice flour
• 25 g mung bean flour or arrowroot
• 250 g sugar
• 500 ml coconut milk
• ½ tsp salt
• 10 pandan leaves
• 150 ml water (for pandan juice)
• 1 tsp jasmine water or vanilla (optional)
• 1 tbsp vegetable oil, for the tin

Tapioca starch (also called tapioca flour) is the base and gives the chew; do not substitute cornflour. Mung bean flour is sold in Thai shops (often in small packets labelled 'green bean flour'); arrowroot or extra rice flour can stand in. Pandan leaves are available fresh or frozen in Asian grocers; pandan extract can be used, but natural pandan juice gives a softer colour and better aroma. For a blue layer, steep 20 dried butterfly pea flowers in the water instead.

iv. Method

1. Cut the pandan leaves into short lengths and blend with the 150 ml water until fine. Squeeze through a cloth or fine sieve to get about 120 ml green juice.
2. In a pan, warm the coconut milk with the sugar and salt just until the sugar dissolves. Cool to room temperature and stir in the jasmine water, if using.
3. In a large bowl, whisk the tapioca starch, rice flour and mung bean flour. Gradually whisk in the cooled coconut milk until completely smooth, then strain.
4. Divide the batter in half. Stir the pandan juice into one half. Add an equal amount of water (about 120 ml) to the white half so the two batters are the same consistency.
5. Set up a steamer at a full boil, wrapping the lid in a cloth. Oil a 20 cm square tin and heat it in the steamer for 3 minutes.
6. Stir the green batter and pour in a thin layer (about 70 ml). Steam for 5 minutes until set. Stir the white batter and pour a layer of the same volume over it; steam for 5 minutes. Continue alternating, stirring each batter before pouring, until you have 9 layers, finishing with green.
7. Steam the final layer for 15 minutes so the whole cake sets through. Remove and cool completely, at least 4 hours.
8. Loosen the edges with an oiled spatula, turn out and cut into diamonds or squares with an oiled knife or plastic knife.

v. Tips & common mistakes

• Stir before every layer. Starch sinks within a minute; unstirred batter makes uneven, watery layers.
• Measure each layer. A small ladle or measuring cup keeps all nine layers the same thickness.
• Steam until just set. Over-steamed layers do not bond and the cake falls apart when cut.
• Wrap the lid. Condensation dripping on the cake pits the surface and leaves watery spots.
• Cool fully before cutting. Warm khanom chan is sticky and tears; cold, it cuts cleanly.
• Do not refrigerate. The starches harden in the fridge, making the cake tough and opaque.

vi. Variations

Khanom chan dok kulap is shaped into rose petals using a cut-out or by rolling the layers. Butterfly pea gives blue layers, and pink layers come from food colouring or rose syrup. Some modern versions add taro or pumpkin purée for flavour and colour.

Compare the regional layer cakes: Indonesian kue lapis, Filipino sapin-sapin and Vietnamese bánh da lợn. Within Thai desserts, see khanom krok and butterfly pea flower pudding, and the Malaysian two-layered seri muka.

vii. Serving & storage

Khanom chan is served at room temperature, cut into small diamonds or squares, on a plate of mixed Thai sweets or as an offering at ceremonies. Children often peel it apart one layer at a time. Thai tea or jasmine tea is the usual accompaniment.

Keep covered at room temperature and eat within 2 days. If it does need to be refrigerated in hot weather, steam the pieces for 5 minutes to restore the soft, translucent texture. It does not freeze well.

ix. More from Thai

• Khanom Krok — coconut-rice pancakes
• Butterfly Pea Pudding — blue flower pudding
• Sankaya — Thai coconut custard
• Kue Lapis — Indonesian layer cake
• Sapin-Sapin — Filipino layered rice cake
• Bánh Da Lợn — Vietnamese layered cake