Beat the eggs with sugar until pale. Mix the dry ingredients and add to the egg mixture. Melt chocolate and butter, then add last.
Distribute the mixture into two 21cm round cake pans and bake for 25-30 minutes at 180°C. Cool and level the cakes with a long knife.
For the cream, ensure butter and cream cheese are at room temperature. Melt whipping cream and chocolate together to make ganache, then cool.
Beat the butter with powdered sugar until pale, add cream cheese, then fold in ganache carefully.
For the mirror glaze, hydrate gelatin in water. Boil glucose, sugar, and water until 103°C. Pour over chopped chocolate, mix, then add condensed milk and gelatin.
Assemble the cake: layer one cake, half the cream, banana slices, second cake, and remaining cream. Chill overnight, then frost with mirror glaze and decorate as desired.