For the chocolate maroni cake, beat eggs with sugar for 5 minutes until foamy. Sift flour and starch together and fold into the egg foam. Mix oil with cocoa until smooth, fold in chopped chestnuts last.
Pour the chocolate mixture into a 20×25 cm baking pan lined with baking paper. Bake at 180 degrees for about 40 minutes.
Cut into small rectangles and eat up while still warm.