Source: Nigella.com, How To Be A Domestic Goddess

Ingredients:
- Half stick soft unsalted butter, plus more for greasing
- 12oz bittersweet chocolate
- three quarters cup sugar
- 4 large eggs, beaten with a pinch of salt
- 1 teaspoon vanilla extract
- third of a cup flour
- 6 individual pudding moulds, buttered
- baking paper
Directions:
Unless you are making these up in advance, preheat the oven to 400F, putting in a baking sheet at the same time. Lay 3 of the moulds on a sheet of doubled baking paper. Draw round them, remove, and then cut out the discs as marked. Press them all into the base of the tins.
Melt the chocolate and let it cool slightly. Cream together the butter and sugar, and gradually beat in the eggs and salt, then the vanilla. Now add the flour, and when all is smoothly combined scrape in the cooled chocolate, blending it to a smooth batter.
Divide the batter between the 6 moulds, quickly whip the baking sheet out of the oven, arrange the little tins on it and replace in the oven. Cook for 10-12 minutes (the extra 2 minutes will be needed if the puddings are fridge-cold when you start) and as soon as you take them out of the oven, tip out these luscious babycakes onto small plates or shallow bowls; hot, chocolate goo will ooze out of them as you break them with a greedy spoon. Serve these with cream, crème fraiche, or ice cream as you so desire.
Serves 6.