2 tablespoon unsalted butter
1 cup milk
3 cooked waxy potatoes, unpeeled and cut in 1/2′ slices
salt and freshly ground pepper, to taste
In a heavy pan over med-low heat, combine the potatoes and milk, and bring to a boil. Simmer gently 20-25 minutes, stirring occasionally, until the potatoes have absorbed all the milk. Gently stir in the butter and seasonings.