When I make dinner like this, there is nothing left!

INGREDIENTS:

5 potatoes, chopped

Water to cover

1 teaspoon salt 200 grams of ham

1 onion

Oil

2 tablespoons butter

2 tablespoons wheat flour

500 ml milk

1 teaspoon salt 1 teaspoon black pepper

1 teaspoon oregano

Grated mozzarella cheese