Peel the chestnuts and chop them finely.
Add butter and sugar to a bowl and cream them together.
Add eggs one at a time, whipping after each addition.
Sift the flour and baking powder, then add them to the batter.
Add the chopped chestnuts and mix well.
Pour the batter into a mold.
Bake in the oven at 180°C for 30–35 minutes.
Let cool to finish.