Radicchio Scalloped Potatoes

3 large baking potatoes, peeled and sliced 1/8 inch thick
8 anchovy halves, well rinsed
1 medium head Royal Rose radicchio, coarsely chopped
4-6 tablespoons butter
Black pepper
Preheat oven to 375°. Butter a 10-inch oval ovenproof dish with 1 tablespoon butter. Cover the bottom with half of the sliced potatoes. Tear the anchovy halves into small pieces and sprinkle half of them over the potatoes. Distribute half of the chopped radicchio evenly over the potatoes and anchovies. Grind fresh pepper over the first layer. Repeat with the remaining potatoes, anchovies and radicchio. Grind more fresh pepper over the second layer. Dot the top with remaining butter. Pour in enough milk to fill the dish slightly less than halfway up the sides. Put the dish on a cookie sheet and into the oven. Bake until there is a crust on top and the potatoes are fork tender, approximately 45-60 minutes.