Wash the pumpkin thoroughly, remove the skin and seeds, then steam it.
Mash the steamed pumpkin until smooth.
Add eggs and sugar, then mix well with a whisk.
Sift in pumpkin, all-purpose flour, baking powder, and cocoa powder, and mix into the batter.
Add vegetable oil (or butter) and milk, and stir until smooth.
Add chocolate chips and mix evenly.
Pour the batter into a mold and bake in a preheated oven at 170°C (340°F) for 30-35 minutes.
Cool before serving.