4 garlic cloves, minced
1 3/4 tsp. salt
1/2 tsp. freshly ground pepper
3-4 tbsp. prepared horseradish (more or less to taste)
1 tbsp. butter
3-4 lbs. Idaho potatoes peeled and very thinly sliced
1 cup caramelized sliced onions
2 cups Cheddar cheese, shredded
2 cups Swiss cheese, shredded
1/4 c. freshly grated Parmesan cheese
Preheat the oven to 350 degrees. In a medium bowl, combine the half-and-half, garlic, salt and pepper. Gradually stir in the horseradish, tasting for strength. Butter the bottom and sides of a 13 x 9-inch non-reactive baking dish. Layer the potatoes in rows to cover the bottom of the dish, overlapping them slightly. Pour the horseradish mixture over the potatoes. Place 1/3 of the caramelized onions over the potatoes. Sprinkle 1/3 of the Cheddar cheese and 1/3 of the Swiss cheese over the potatoes and onions. Repeat with another layer of potatoes, more horseradish mixture, caramelized onions, Cheddar cheese and Swiss cheese. Repeat with a third layer in the same order as the first two. Bake in the upper third of the oven for about 30 minutes, or until bubbling. Sprinkle the Parmesan cheese over the top and bake for about 15-20 minutes longer, or until the potatoes are tender and the top is lightly browned. Cover the dish with foil and let stand in a warm place for about 10 minutes before serving.
