Clean the pumpkin filling and cut it into cubes, put it in a pot with enough water to cover and boil it together with the sugar; after it is boiled, drain it well and grind it with the mashed potatoes.
Let it cool very well and then mix with condensed milk and spices to taste.
In a bowl, mix the butter with the egg and milk, add the sugar and spices, stir continuously until smooth, gradually adding flour and a pinch of salt, until a homogeneous and non-sticky dough results.
Let it rest for 30 minutes in the fridge. Spread the dough on the floured table, add it in a pan greased with butter and lined with flour.
From the remaining dough I spread it in a thin sheet, greased it with butter and powdered it with cinnamon and rolled it as tight as possible, cut slices about 1 cm thick and added on top, greased with beaten egg yolk.
Prick with a fork and add the filling, put the tray in the preheated oven for about 30-40 minutes until the edge is nicely browned.