This is a baked dessert from South Africa, and it's delicious. It has a spongy interior and a caramelized outside texture. There are several versions of this recipe, most differing in the sweetened sauce drizzled on top. This version is topped with a luscious sauce made from Amarula, a creamy liqueur made in South Africa. I think the sauce makes a splendid addition to this classic dessert. In South Africa, it's served with sweetened custard on the side. But you could also serve it with whipped cream or vanilla ice cream, if you wish.
Preheat oven to 350°F. Grease 8-inch square cake pan; set aside.
Add eggs, orange zest, sugar, butter and jam to a large bowl, and beat until light and fluffy. Add vinegar and milk, and beat just enough to incorporate into the batter.
In another bowl, sift together the flour, baking soda and salt. Gradually fold the flour mixture into the egg mixture. The mixture might be a little runny, that's OK.
Pour batter into prepared cake pan. Bake at 350°F for 25 to 30 minutes or until a toothpick insert in center comes out clean.
While cake is baking, prepare the Amarula sauce. Combine the butter, cream and sugar in a saucepan over low heat for about 4 to 5 minutes, and stir until the sugar is dissolved and the sauce has thickened. Remove saucepan from heat, and stir in the Amarula liqueur.
When the pudding is done baking, remove it from the oven and slowly pour the Amarula sauce over the pudding while it's still hot, letting the pudding get saturated with the sauce.
Serve hot, with fresh custard (or whipped cream or vanilla ice cream) on the side.