Start by slicing the previously peeled Kabocha squash into smaller pieces.
In a steamer pot, add the hot water, turn on the heat at medium power, add all the pieces of squash in the top tray, cover the pot and let them cook for 35 minutes, just like shown in the video.
In a bowl, add the milk at room temperature and the cornstarch, mix until combined.
Once the pieces of squash have cooked through, transfer them all to a large bowl and using a fork, mash them well until a smooth puree is formed.
Transfer this squash puree to a skillet, turn on the heat at medium-low power, pour in the milk and cornstarch mixture and stir well.
Next, pour in another 400ml of milk and keep stirring until the mixture gains consistency.
After that, add the icing sugar and stir very well for another 2 minutes.
Next, transfer this mixture to holes in a cupcake tray.
Let it all cool down until room temperature is reached.
Serve.