Mix the flour, salt, sugar and yeast in a bowl. Add the butter and milk, mix and knead into a soft, smooth dough. Place the dough in the prepared tin and press flat. Cover and leave to rise at room temperature for approx. 1 hr. until doubled in size. Using your fingertips, press little hollows into the surface of the dough.
For the topping
Combine the cream and egg yolk, stir well. Pour half of the mixture over the dough. Arrange the sugar cubes on top of the dough and top each with a little knob of butter.
Bake for approx. 10 mins. in the centre of an oven preheated to 200°C. Remove the cake and top with the remaining cream and egg mixture.
Finish cooking for approx. 10 mins., remove the cake, lift out of the flan tin, allow to cool a little on a cooling rack and serve slightly warm.