A custard pie is any type of uncooked custard mixture added to an uncooked or partially cooked crust and baked together. In North America, custard pie commonly refers to a plain mixture of milk, eggs, sugar, salt, vanilla extract and sometimes nutmeg combined with a pie crust. It is distinctly different from a cream pie, which contains cooked custard poured into a cooled, precooked crust. In the United Kingdom, the comical or political act of pieing is conventionally done with a "custard pie". Some common custard pies include pumpkin pie, lemon and buttermilk chess pie, and coconut custard. True custard is defined as a liquid thickened with eggs. Due to the often large number of whole eggs in custard pie it is a very rich pie.