A buttercream filling and chocolate glaze turn this simple sponge into something special This simple cake requires little more than stirring, baking and eating Credit : Haarala Hamilton Diana Henry The Telegraph's award-winning cookery writer Diana Henry is the Telegraph’s much-loved cookery writer. She shares recipes each week, for everything from speedy family dinners to special menus that friends will remember for months. She is also a regular broadcaster on BBC Radio 4, and her journalism and recipe books, including Simple and How to Eat a Peach, are multi-award-winning. A mother of two sons, Diana can satisfy even the fussiest of eaters.    See more Published 21 May 2026 9:54am BST As less air is incorporated with ‘all-in-one’ cakes – instead of spending time beating the butter and sugar together, everything is combined from the outset – some baking powder is added, even though self-raising flour is used.…