First beat butter with sugar and eggs until fluffy. The eggs do not need to be separated, but you must then stir the mass very long until the volume has at least doubled.
Then carefully stir in the melted chocolate, which is no longer hot. Then fold in the flour mixed with cocoa and baking powder.
Spread the batter on a greased baking sheet and bake at 160 °C for about 20 minutes (test with a stick).
Brush the still hot cake with jam. Then let the cake cool down a bit.
In the meantime, melt the chocolate and butter in a saucepan and then coat the cake with the glaze.