Clean the kabocha pumpkin and steam it in a steamer.
Peel the steamed kabocha and mash it well.
Add sugar, eggs, and milk to the mashed pumpkin and mix thoroughly.
Add flour and baking powder to make the batter.
Grease the pan with butter and pour in the batter.
Bake in the oven at 180°C for 30 minutes.
Let the finished cake cool and slice it.