Potato Horseradish Gratin With Caramelized Onions

Not sure where this recipe came from, as I copied it at my sisters because I thought it looked good. Haven't tried it yet, but surely that can't be enough salt for 2 1/2 lbs of potatoes! Otherwise, sounds good with the horseradish.

• Ready In: 1 hr 20 mins
• Yields: 1 casserole

Ingredients

• 2 1⁄2 lbs  medium sized baking potatoes
• 1  teaspoon salt, divided
• 1  teaspoon pepper, divided
• 2  cups half-and-half
• 1⁄2 cup  creamed horseradish
• 1⁄4 cup butter
• 2  large onions, thinly sliced
• 1  teaspoon sugar
• 1  tablespoon  balsamic vinegar
• 1  cup  shredded swiss cheese
• 1⁄4 cup  chopped fresh parsley, divided

Directions

1. Cook potatoes in boiling water to cover; about 20 minutes or until almost tender. Drain and cool slightly. Peel potatoes and cut into 1/4 inch thick slices. Arrange potaotes in a lightly greased 13x9 inch casserole dish. Sprinkle with 1/2 t salt and 1/2 t pepper.
2. Stir together the half and half and the horseradish and pour over potatoes.
3. Bake, covered at 400 degrees for 40 minutes.
4. Melt butter in large skillet over medium heat. Add onion, remaining salt and pepper and sugar. Saute and top potatoes then cheese and run under broiler.