This rich cream cake is a Slovak dish. Some recipes use a digestive-biscuit base, others put puff pastry on top and underneath, and some also add melted chocolate.
Pour the milk into a pan and add the custard powder, 200g of icing sugar, vanilla sugar, egg yolks, rum and flour.
Beat using an electric mixer, then put over medium heat and cook, beating, until the mixture becomes very thick. Leave to cool. Preheat the oven to 200°C/400°F/Gas 6