A favourite version from ” Simon Hopkinson Cooks” by Simon Hopkinson.
Preheat the oven to 190C/gas mark 5.Grease a shallow, ovenproof dish (handsome enough to transfer from oven to table) with half the softened butter. Fill the base of it with the onions.
Using a pair of scissors, snip the anchovies into small pieces and distribute them over the onions. Pour over the juice from one of the tins.
Cover with the prepared potatoes, press them down lightly and season. Pour over the cream and then quietly tap the dish a couple of times on a wooden surface to settle the assembly.
Sprinkle the breadcrumbs evenly over the surface and dot with the remaining softened butter.
Bake in the oven for anything between 45 minutes and 1 hour, or until the surface of the dish is nicely gilded, crusted and bubbling around the edges. Serve as is, all on its own.