3 tablespoons butter, divided
1 large onion, halved and sliced
1 pound green cabbage, cored and sliced thinly
Salt and pepper
1 tablespoon apple cider vinegar
2 pounds potatoes, baked
1 1/2 tablespoons flour
1 cup milk
1/8 teaspoon freshly grated nutmeg
Preheat oven to 400°F. Heat a dash olive oil in a large pot over medium heat. Add 2 tablespoons butter, let melt, and add onion slices. Toss and cook, stirring occasionally, until soft, about 10 minutes. Stir in 1 teaspoon salt and 1/4 teaspoon pepper and toss in cabbage. Stir until completely mixed and cabbage begins to wilt. Pour in vinegar and 1 tablespoon water, cover pot, and turn heat to low. Cook 10 minutes, stirring, until tender.
Peel potatoes and mash roughly with a fork. Melt remaining tablespoon butter in 10- or 12-inch skillet. Add flour all at once, turn the heat to medium low, and cook, stirring constantly, for 2 minutes. Add milk and cook, stirring, until the mixture thickens.
Turn off heat and stir potatoes into the sauce. Season with nutmeg, and stir in the cabbage and onions. When thoroughly mixed, smooth the top with a spoon and bake 15 to 20 minutes.
We thank SeriousEats.com for this recipe.