Start cooking about 1h before serving.
4 servings
Heat the oven at 180 degrees and boil the kettle. Butter a heat-proof dish and get ready a roasting tray large enough to contain the pudding dish.
Cream the butter and sugar. Mix with the zest, juice, egg yolks and flour. The mix may look a little curdled. Separately, beat the egg whites to soft peaks then mix carefully with the citrus mixture.
Pour into the prepared dish, pour boiling water in the roasting tray so it comes half-way up the pudding dish. Bake for 35-40 mins until it’s golden on top, but still creamy at the bottom.
Serve immediately.