Mix the milk and heavy cream, and from this quantity take 1 cup (needed for mixing with starch and sugar). The rest of the mixture boil and when it boils, add the starch and cook well. The cream is relatively quickly thickens and did not take long to cook, maybe about 2-3 minutes.
Cooked cream divided into two parts.
In the first part add dark chocolate and stir well till the chocolate is melted, and in the second part add white chocolate and also mix well till the chocolate is melted.
At the bottom of the mold for the cake put the biscuits that are soaked in cold milk and immediately put first dark cream(untill is hot) , then the white cream. Leave the cake in the refrigerator to be well tightened.