Line one 7 inch square pan with plastic sheet. Make sure the plastic sheet is much higher than the pan.
To make the chocolate custard, lightly beat the eggs in the mixing bowl. Put in the cocoa powder, vanilla flavour and sweetened creamer and whisk until well combined.
Pour the chocolate custard and butter into a non-stick pan at medium low heat. Stir the mixture until thickens.
Spread a thin layer of custard into the pan. Arrange Marie biscuit on the custard. Repeat the step until all custard and biscuits are used up.
Fold in the high collars of the plastic sheet. Press down and compact the cake with hands.
Chill in fridge overnight before cutting.