First, make the cream. Heat the milk up with the sugar. Mix the starch with a little water to make a sludge.
Once the milk comes to a boil, pour in the mixture and stir until thickened. Remove from the stove and add the butter, stir until it melts.
In a large oven dish, arrange a layer of biscuits, pour on 1 ladle of cream on top. Arrange a 2nd layer of biscuits, then cream and so on until out of ingredients.
Finish off with cream, sprinkle crumbled biscuits on top. Leave it to harden, cut it into slices and serve.