Put the cube of margarine, sugar, water and cocoa together in a medium-sized saucepan and bring to the boil, stirring occasionally. Then let it cool down for at least 20 minutes (30 minutes for a pan with a sandwich base).
Then stir in the remaining ingredients. Put the whole thing in a greased bundt cake tin lined with breadcrumbs and bake at 190 ° C (preheated, fan-assisted) for about 45 minutes (chopstick test).