Treacle sponge is a traditional English dessert made by steaming pudding until it becomes a light cake that is cooked with a coating of sweet syrup. The syrup, which is called treacle, is sweet in a way that is more subtle than pure sugar and is baked in a layer under the pudding, as well as being poured on top after the sponge has been removed from the cooking dish. It is easy to prepare treacle sponge, with the recipe not only requiring very little preparation, but also being very forgiving about cooking times and ingredients. The finished treacle sponge is usually served with custard, whipped cream, or drenched in treacle that has been flavored.
The sweetness in the steamed pudding comes mainly from two sources, caster or brown sugar, and the thick syrup known as treacle. Treacle is the liquid that remains after most of the sugar crystals have been extracted from the sugar liquor produced while processing raw sugar. It comes in a sweet, lightly colored form known as golden syrup, and a much more robust and darker-colored form called black treacle. Most treacle sponge recipes use the lighter golden syrup.
The first step in making a treacle sponge is to create the pudding. Typical ingredients include softened butter, flour, eggs, caster sugar and sometimes milk. For the pudding to form correctly and cook properly, the butter used must be as soft as possible without actually being melted. The flour that is used is normally sifted, again to ensure that the pudding combines into an even and smooth batter. Milk can be used, as can vanilla beans or vanilla extract, to bring out a more cake-like taste.
A pan is prepared by greasing the interior with butter and then pouring a thin layer of treacle into the bottom. Breadcrumbs are sometimes pressed into the syrup so the final treacle sponge has a kind of sweet crust on the top when done cooking. The pudding is poured into the baking dish and the dish is covered tightly with foil to prevent water from getting into the pan.
The pan containing the pudding is then placed in a steamer or large pot and steamed for an hour or more until it has set. Once it is done, the treacle sponge is allowed to rest and cool for a short time before it is turned upside down and unmolded onto a serving plate. More treacle is poured over top of the sponge. Some commercially available versions of treacle are flavored with ingredients such as vanilla or toffee and can be used to give the cake a different taste.
When served, treacle sponge usually is accompanied by a simple custard that is made from the same caster or brown sugar that is used in the sponge. Whipped cream can be placed on the side, as well. Butter, fresh fruit and a small amount of heavy cream also can be served with the dessert.