Soak adzuki beans in water enough to cover overnight.
Drain then put into a pot. Pour in 500ml of water. Bring it to a boil then leave to simmer for about 90 mins until cooked (You may use a pressure cooker/instant pot to reduce the cooking time).
Make the bean paste
Put drained beans into a food processor. Add white sugar, dark brown sugar and butter (or lard, coconut oil). Blend on high speed into a fine paste. You may need to add a little water to make blending easier. However, only add as little as necessary.
Transfer the soft paste into a non-stick pan. Cook over medium-high heat while stirring and flipping constantly to avoid burning. Once the paste becomes dark, dry and holds in shape, remove to cool (please refer to the video for the desired consistency).
Cook the squash (skip if using canned pumpkin puree)
Cut the butternut squash into chunks (skin & seeds removed). Steam for 15 mins until fork tender.
Make the dough
Put the cooked squash into a food processor. Add sugar and oil. Blend on high speed until it turns into a fine puree.
Add glutinous rice flour in batches. Run the food processor on medium speed until a dough forms. It should be very soft but not sticky. Depending on the water content of the cooked squash, you may not need to use all the flour suggested in the recipe, or you may need to add a little more. Please feel free to adjust accordingly.
Assemble the cakes
Divide the dough into 16 equal pieces. Then shape each into a ball. Repeat the same procedure to make 16 balls with the red bean paste.
Flatten one dough ball into a disc. Place a piece of filling in the middle. Gently push the edge of the dough upwards to cover the filling and seal completely.
Use the spine of a butter knife to create indentations all around to imitate a pumpkin. Then insert a piece of raisin on top as the “stem”(please refer to the video below).
Steam the cakes
Lay the assembled cakes in steamer baskets lined with parchment paper (or brushed with a thin layer of oil if using metal/plastic steamer baskets).
Bring water to a boil in a wok/pot, place in the baskets. Cover and steam for 10 mins over medium-high heat.
Serve, store & make ahead
When cooked, leave the cakes to cool in the baskets for 5 mins then serve (Otherwise, they are very sticky to touch). These pumpkin cakes can be served warm or at room temperature.
You may keep them in the fridge for 3 days or in the freezer for 2 months.
Reheat refrigerated or frozen pumpkin cakes in the steamer until they become soft again.
Make ahead: Lay assembled, uncooked pumpkin cakes on a tray lined with parchment paper. Put into the freezer. Once completely frozen, transfer them into an air-tight bag/container. Store in the freezer for 2 months. Steam them without defrosting for 15 mins.
Video
Notes
1. To make the paste vegan friendly, you may replace butter with coconut oil. In this case, reduce its quantity by half as the coconut flavour can be a little overpowering.2. To achieve a bright colour for the dough, I use butternut squash for its orange flesh. Pie pumpkin (aka sugar pumpkin) works too but the colour of the dough would come out a bit lighter. Alternatively, use canned pumpkin puree.3. Glutinous rice flour is finely ground white powder made of glutinous rice (aka sticky rice, sweet rice). Despite its misleading name, it’s completely gluten-free.