if using condensed milk, place sealed tin in a pot of rapidly boiling water for two hours to make your own caramel.
place the eggs and sugar in a fairly large bowl, over a pan of hot, not boiling water. an electric mixer is ideal to use here. whisk until the mixture is really stiff and will leave a good trail; it will take between 10 – 20 minutes by hand. sieve the flour and cocoa together then sieve it again into the bowl. fold in carefully so that there are no pockets of flour left.
divide the mixture between the tins and level off the surface by tilting the tins.. do 