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kue bolu kukus

Steamed Indonesian Cupcakes (Kue Bolu Kukus)

Light, fluffy, and slightly coconutty — a traditional Indonesian steamed cake that “blooms” beautifully when made right.
Kue Bolu Kukus is Indonesia’s answer to the cupcake — steamed instead of baked, airy instead of dense. This dessert is made with soda water, coconut milk (santan), and eggs, resulting in a soft, tender crumb that splits open like a blooming flower when steamed. It’s a beloved treat for family gatherings, tea time, or festive celebrations.
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Prep Time 15 minutes
Cook Time 15 minutes
Total Time 30 minutes
Servings: 10 Cupcakes
Course: Dessert, Snack
Cuisine: Indonesian
Calories: 180
Ingredients Method Notes

Ingredients
  

Main Batter:
  • 1 cup + 2 tablespoons 250 g all-purpose flour (tepung terigu protein sedang — medium-protein wheat flour)
  • 1¼ cups 250 g granulated sugar (gula pasir)
  • 3 large eggs telur ayam
  • ⅔ cup 150 ml unsweetened coconut milk (santan kental) – full-fat preferred
  • ⅔ cup 150 ml plain soda water (air soda tawar) – freshly opened for carbonation
  • ½ teaspoon cake emulsifier SP or Ovalet – helps stabilize the batter
  • Cupcake liners or parchment paper kertas minyak for steaming
  • Optional: few drops of food coloring for a marbled look

Instruction
 

  1. Prepare the steamer
    Fill your steamer pot with water and bring to a rolling boil. Wrap the lid with a clean kitchen towel to prevent condensation from dripping onto the cakes.
  2. Whip the base mixture
    In a large mixing bowl, combine eggs, sugar, and SP (emulsifier). Beat with a hand or stand mixer on high speed for about 10 minutes, or until the mixture becomes thick, pale, and tripled in volume.
  3. Incorporate the dry ingredients
    Sift in the flour gradually while mixing on low speed or folding gently with a spatula.
  4. Add the liquids
    Pour in the coconut milk and soda water, alternating between the two while gently folding the batter until just combined. Do not overmix — this will deflate the air bubbles.
  5. Color the batter (optional)
    If you want colorful cupcakes, divide the batter and tint one part with food coloring. You can layer white–colored–white for a classic tri-layer look.
  6. Fill the molds
    Line your molds or cups with cupcake liners and fill them to the top. Steamed cakes need full molds to expand and bloom.
    bolu kukus mold
  7. Steam the cakes
    Place the molds in the steamer, cover tightly, and steam over high heat for 15 minutes. Avoid opening the lid during this time.
  8. Cool and serve
    Remove from the steamer, cool for a few minutes, and gently remove from the molds. Serve warm or at room temperature with tea or coffee.

Notes

  • Emulsifier (SP or Ovalet):
    This is a cake stabilizer commonly used in Southeast Asia. You can substitute it with 1 teaspoon of cornstarch or omit it entirely if whipping the eggs properly. The texture will still be soft.
  • Coconut milk (santan):
    Use full-fat canned coconut milk like Thai brands (Aroy-D, Chaokoh) for the same richness as Indonesian santan.
  • Soda water:
    Acts as a natural leavening agent. Use plain carbonated water or club soda, not sweetened soda.
  • Steaming tips:
    • Keep the heat high throughout steaming.
    • Avoid lifting the lid before 15 minutes — sudden temperature drops can make the cupcakes collapse.
    • Wrap the lid with a towel to prevent dripping water.
  • Flavor ideas:
    Try adding vanilla extract, pandan essence, or a few drops of rose water for regional flavor variations.