On a cutting board, cut 5 potatoes in slices, that way. Transfer the potatoes to a pan and cover it with water. Add salt to taste, mix it, cover it and let it cook for 10 minutes.
In another pan, add 2 tablespoons of butter and let it melts. When the butter melts, add 3 tablespoons of wheat flour and mix it well. After that, add 350ml of milk and 125ml of milk cream and mix it again.
Now add salt and black pepper to taste, and keep stirring in médium heat until it thickens.
In a refractory, do the same layer of potatoes. Next, add the sauce and spread it well. Then add the ham and grated mozzarela to taste. Repete the same process in the second layer. Finish with the cream, spread it well and add grated mozzarela and oregano to taste.
Take if to preheated oven at 356°F for about 30 minutes.