Egg-based custards are important both as sweet sauces and components in other dishes. For sauces, they are generally milk-based, or use small proportions of cream, and may be made with egg yolks rather than whole eggs. They can be added to fools and form an essential layer in trifle. See fools and trifle. The custard powder variety is often substituted; it also provides the base for banana custard, with slices of that fruit added. The notion of custard as a sauce runs deep in British food traditions, served alongside the numerous baked or steamed puddings traditional to dinner. Confusingly, the British would regard American packaged “pudding” mixes, which are also popular in parts of Europe and eastern Asia, as a form of custard.