Heat the milk until lukewarm; mix the flour, yeast, sugar and salt together in a bowl, add the butter and milk and mix everything together to form a dough. Turn out onto an un-floured surface and knead for 5-10 minutes until smooth and elastic - because the dough is made with plain rather than strong flour it will not be as elastic as usual bread dough.
Place the dough in a clean bowl, cover and leave to rise for about an hour until doubled in size.
Butter a 23-28cm (9-11in) round springform tin then press the dough out evenly in the tin so that it covers the base. Cover and set aside to prove for about half an hour until puffy.
Meanwhile, preheat the oven to 190C/375F/gas mark 5 and make the topping.
Melt the butter in a pan over a low heat, set aside to cool slightly; whisk together the eggs, sugar and flour in a bowl until smooth then add the butter and mix until well combined.
Pour the topping mixture evenly over the risen dough then bake on the lower shelf of the preheated oven for about 25 minutes if using a 28cm tin, or 30-40 minutes if using a 23cm tin. It should be golden brown and the topping should be set; if the top browns before it is cooked through then cover the cake with foil.
Remove from the oven and leave to cool in the tin before turning out and slicing.
You will need a 23-28cm (9-11in) springform cake tin