These are a perfect (if slightly better) replica of Costa's Lemon Curd Muffins. Think big, moist zesty muffins, filled with a thick lemon curd. That said, these are cheaper than your coffee shop version and are super easy to make. If you have ever stepped into a Costa Coffee shop in the UK, you may have noticed their bright and cheerful lemon curd muffins displayed alongside lattes and cappuccinos.