Japanese Steamed Cakes (Mushi Pan)

Sweet Potato (If using a different filling, skip these steps)

1. Cut 80 g Japanese sweet potato into small cubes, then place in a bowl of cold water for 5 minutes to remove the excess starch.
2. Drain and place the cubes in a saucepan with 1 tbsp sugar. Add enough water to just about cover and simmer without a lid for about 5 minutes or until par-boiled. (Be careful not to cook too much or they will break when mixed with the mushi-pan batter.)
3. Drain any excess liquid and set aside for later.

Mushi Pan

1. Mix 60 g cake flour, 2 tbsp cornstarch, 1 tsp baking powder and 1 pinch salt together in a bowl. For chocolate mushi pan, swap the cornstarch for cocoa powder. For matcha mushi pan, half the starch and replace with matcha powder.
2. In a separate bowl, add 80 ml milk. (If flavoring with tea, warm the milk and steep the tea for 2-5 minutes or until strong enough to your liking then strain.) Add 40 g sugar, ½ tbsp oil and a few drops of vanilla essence (or flavoring of your choice) and whisk until the sugar has dissolved.
3. Sift the dry ingredients into the wet ingredients and whisk until smooth.
4. Fold in about 3/4 of the sweet potato (or filling of choice), saving the other 1/4 to place on top.
5. Fill your steamer with water and bring to a boil over a high heat. Wrap the lid with a clean kitchen towel to prevent water droplets falling on the mushi pan. (If you don't have a steamer, use a deep pan with a lid and place a wire rack or similar to elevate the mushi pan.)
6. Line ramekins with cupcake cases and then spoon the mixture inside. Place the remaining sweet potato pieces (or filling of choice) on the top.
7. Once the water in the steamer is boiling rapidly, carefully place the mushi pan inside the steaming basket (be careful of the steam, use gloves or tongs to protect your skin). Leave space between them to prevent them from merging together when they expand. Cover with the lid and steam for 12 minutes on high.
8. After 12 minutes, turn off the heat and remove the mushi pan from the steaming basket. I used tongs and a spatula to remove them. Transfer to a wire rack and leave to cool.
9. Enjoy!