I have seen many different versions of this and made two, one from a kids’ cookbook that is a chocolate version that just isn’t chocolaty enough and the Nigella version. Here’s my conflagration of the two:
Keifel’s Favorite Sauce Cake
1 cup plus 2 tablespoons unbleached, all purpose flour
2 teaspoons baking powder
1/4 teaspoon salt
3/4 cup dark brown sugar (do not substitute light brown, for those UK folks I think this is dark muscovado sugar)
1 teaspoon of vanilla extract
1/2 cup milk (whole milk is probably best but I only have 1% in the house and it seems to work fine)
1/2 cup unsalted butter, melted and cooled
2/3 cup dark brown sugar
2 1/4 boiling water
2 tablespoons unsalted butter
Butter a 2 quart baking dish, I use a round souffle dish for this, and set the oven to 375 degrees F. In a medium sized-bowl, whisk together the flour, db sugar, salt and baking powder. (I am usually melting the butter in the microwave during this step). In a 2 or 4 cup capacity measuring cup, measure the 1/2 cup of milk, the vanilla and crack in the egg; whisk to combine. Pour the melted butter into this and whisk again. Pour the wet ingredients over the dry and stir just to combine. Pour, or more accurately scrape, this batter into the prepared baking dish. Sprinkle with the 2/3 cup of sugar and dot with the 2 tablespoons of butter. It won’t look like very much in the dish, but it rises quite a bit. Pour the hot water over this. It does seem a weird thing to do and looks suspect but it works. Bake for about 45 minutes, until the cake has risen above the sauce and browned on top. I advise checking it at 40 minutes though the cake sometimes has to go as long as 55.
Notes: Nigella recommends pouring custard as an accompaniment, which I am sure would be divine, but vanilla bean ice cream is our side of choice. Nigella also adds a 1/2 cup of chopped dates to the batter. I found they absorb all the sauce, but you could soak them either in hot water or rum. Of course, I would recommend the rum. Nigella also originally called for self-rising flour, if you use that skip the salt and baking powder. If you only have salted butter, skip the salt in the batter.