I made Nigella's Chocolate Guinness cake for the first time after a friend at work made it. I am not a chocolate fan and initially thought that I would not like it. What a surprise I got! The cake was moist and not overly sweet, which I liked. My query is regarding the method where it says to melt the butter with the Guinness (I did it on a low heat) then add the other ingredients. However you do not state whether you keep the heat on still whilst add other ingredients or not? I did leave it on but would like to know whether I should have left it on until all ingredients were added or only after melting the butter? Thank you, Jane
Nigella's Chocolate Guinness Cake uses the "melting" method for cakes, where the fat is melted before the other ingredients are added. Generally for these type of cakes you melt the fat and any other ingredients that need melting (such as sugar) and then remove the saucepan from the heat and add the other ingredients. In particulalr you should add any eggs off the heat, as if the mixture is too hot then the eggs could curdle.
You are right to use a low heat to heat the Guinness and butter mixture, as it will prevent it from becoming too hot. For this particular cake it doesn't matter too much if the other ingredients are added on or off the heat but for preference we would suggest taking the pan off the heat as it is usually more convenient not to have to add the remaining ingredients while the pan is still on the stove.
We would also mention that, if possible, you should let the sour cream stand out of the fridge for about 30 minutes before using it, to let it loose some of its chill.