Step 1

Fill a 12-inch skillet or wok with about 2 inches of water, then place a 10-inch bamboo or metal steamer basket in the skillet. Make sure the water doesn’t touch the bottom insert. If it does, remove some of the water. Leave the steamer setup on the stove. Spray ten 3-inch fluted egg tart molds with nonstick cooking spray and set aside.

Step 2

Whisk the brown sugar, oil and 3/4 cup hot water in a large mixing bowl until the sugar dissolves, about 1 minute. Set aside the sugar syrup until completely cool, about 10 minutes.

Step 3

When the sugar syrup is ready, sift the all-purpose flour and rice flour into the syrup in 3 additions, whisking between each addition until there are no dry spots. Stir together the baking powder and 1 tablespoon cold water in a small bowl until there are no dry clumps of baking powder. Whisk the baking powder slurry into the batter in 3 additions until there are no streaks of slurry. Fill the prepared egg tart molds to the top (about 1/4 cup of batter per mold).

Step 4

Bring the water in the skillet to a rolling boiling water over high heat. Set 5 of the molds in the steamer basket, cover and steam until the cakes rise and the tops crack open and resemble a flower, about 15 minutes. (Don’t open the lid while the cakes cook; doing so interferes with the rising.) Transfer the molds to a cooling rack. Replenish the water in the skillet as needed and bring to a rolling boil over high heat. Set the remaining 5 molds in the steamer basket and repeat the steaming process.

Step 5

Serve the cakes warm or at room temperature, unmolding them only when you are ready to eat them. They can be kept, covered in their molds, in the refrigerator for up to a week and reheated by steaming over simmering water for about 10 minutes.