Can I substitute olive oil for butter in Nigella's Lemon Polenta Cake? If so, how much?
In some circumstances oil can be substituted for butter in cakes but this has to be done very carefully. Usually it will work in a cake that is made using melted butter, and you need to substitute the butter with a combination of oil and another dairy ingredient, as using the same amount of oil for butter can result in a greasy cake. A vegan margarine can usually be used in place of the butter, if you need to remove the dairy element (and if the cake doesn't contain any other dairy ingredients).
However in Nigella's Lemon Polenta Cake (from KITCHEN) the 200g butter can be replaced with 150ml light olive oil. Beat the oil and sugar together until slightly paler in colour, before continuing with the recipe.
If you would like to try another dairy and gluten free cake then we would suggest Nigella's Chocolate Olive Oil Cake.