7cupsthinly sliced, peeled russet potatoes (about 4 large potatoes)
2cupsdiced ham
1cupshredded sharp cheddar cheese
Instructions
Heat a large skillet over medium heat. Add 2 tablespoons butter and melt. Add sliced onions and stir to coat. Cook for 5 minutes, stirring often. Sprinkle with 1 teaspoon kosher salt and 1/4 teaspoon pepper. Lower heat to low and continue cooking until deeply golden and very soft, about 30 minutes or up to 45 minutes, stirring every 5 minutes.
Preheat oven to 350 degrees F. Meanwhile, make the bechamel sauce. Melt the butter in a medium saucepan over medium heat. Sprinkle in flour and cook for 1 minute. Stir in half the milk and cook, stirring often, until thickened enough to coat the back of a spoon. Add remaining milk and cook again until thickened.
To assemble. Layer half of the potatoes in a 9x9 pan. Spread half the caramelized onions over the potatoes. Sprinkle half the ham over the onions. Evenly drizzle half the sauce. Continue layers again. Top with shredded cheese. Cover lightly with foil.
Bake with foil for 40 minutes. Remove foil and bake 30 minutes. Allow to rest for 5 minutes before serving.