• 9 tablespoons butter
  • 1 tablespoon olive oil
  • 2 medium onions, thinly sliced
  • ¼ teaspoon sugar
  • salt and ground pepper
  • 4 large Idaho potatoes peeled, cut crosswise into 1/4 inch slices
  • ¾ cup flour
  • 2 cups milk
  • ¼ cup chopped parsley (fresh)
  • ¼ cup grated parmesan cheese


Heat 3 tablespoons of the butter and the olive oil in a large skillet over medium heat. Add the onions and the sugar, season with salt and pepper and reduce the hat to medium-low. Cook, stirring occasionally, until the onions are golden brown and caramelized, 30 to 40 minutes. Remove from heat and set aside.

Preheat oven to 350°. Lightly grease a 2-quart casserole. Alternate layers of the potatoes, caramelized onions, 2 tablespoons of flour, salt and pepper to taste, and dot with some of the remaining butter. Repeat until the casserole if 3/4 full, ending with a generous coating of flour. Add enough milk to cover. Sprinkle with parsley and cheese. Place the casserole on a baking sheet and bake until nicely browned and bubbly, about 1 1/2 hours. Serve hot.