I am a learner baker and am a very big fan of Nigella's. I never miss any of her shows on TV. I had a query about vegetable shortening which is mentioned in some cake recipes. I can't find any at cake supply stores. I also had a problem with the frosting that I made during the summer as it started melting badly. How can I substitute shortening? I am a vegetarian but don't mind eggs. Also I wanted to ask about marshmallows. Do you know what are they called in India and whether they are available at all?
Vegetable shortening is hydrogenated vegetable fat (vegetable oil that comes in a solid block and is usually white in colour). We understand that the brand Dalda is available in India, and some larger supermarkets may also have the American brand Crisco. Nigella doesn't normally use vegetable shortening in cakes and buttercream but prefers butter as it has a better flavour and you should be able to use butter as an alternative in most recipes.
Shortening is often used in shortcrust pastry recipes, along with butter, as it helps to gives a flaky crust. But again you could just use all butter. For buttercreams temperature would be key, regardless of whether you are using shortening or butter. If it is too warm the buttercream will melt. In very hot weather you will probably need to make the buttercream, use it and refrigerate the frosted cakes very quickly.
Marshmallows do go by the name of marshmallows in India but we understand that they can be difficult to find. Also most marshmallows are made with gelatine, which is derived from animals, so they are not suitable for vegetarians. If you can find marshmallows then you need to check that they are made with agar agar, or another vegetarian alternative. The related recipe link is for homemade traditional marshmallows.