Ingredients
3 tbsp. unsalted butter
6 large onions (about 1 1/2 lbs.) thinly sliced
2 tins anchovies (1.7 oz/48 g each), drained and diced
1/2 tsp. freshly ground black pepper
1 1/2 cups whipping cream or crème fraiche
1 cup breadcrumbs
3 tbsp. melted unsalted butter
4 large baking potatoes (such as Idaho), peeled and cut into julienne strips (about 1/4 x 2 in.)
Preparation
In a large skillet, over medium-high heat, melt butter. Cook onions until tender, 8-10 minutes. Stir in anchovies and pepper; cook 2 minutes. Reserve.
In a small saucepan, over medium heat, heat cream until it comes just to a boil; reserve.
Combine breadcrumbs and melted butter; reserve.
In a shallow, buttered 9x13-inch baking dish (or 3-qt/3L) casserole dish, arrange half the potatoes. Spread half the onion mixture on top. Repeat. Pour cream over top and shake gently to distribute evenly. Sprinkle with bread crumbs.
Place casseroleon a baking sheet and bake in a preheated 400F/200C oven until potatoes are very tender, 40-50 minutes. Allow to rest 15 minutes before serving.
