The best tips for baking the British, open-top pie called a custard tart include pre-baking the pastry shell to avoid having a soggy crust. It's also important that fresh milk and eggs rather than a packaged mix be used to prepare the custard filling for the best result. Although the classic custard tart is a fruit-based dessert, more savory vegetable pies can also be created from the basic method and ingredients.
Vegetables such as leeks, asparagus and green beans all work well in a savory custard tart. The addition of lemon juice as well as using less sugar in the filling are easy adjustments that can be made to the custard recipe to make it suitable for a vegetable tart. Fresh herbs such as tarragon should be chopped and used in a vegetable custard tart to add flavor.
For custard dessert tarts, sugar rather than honey tends to work best in the filling for baking. It's crucial not to go overboard on the amount of sugar though, or it may turn flat and sticky in the baking process. While sliced apples, peaches and apricots are commonly used in a custard tart, other fruits such as plums and strawberries can also work. A generous amount of nutmeg should be sprinkled on top of custard dessert tarts. To add crunch, flavor and interest, a thin layer of slivered almonds may be added on top of the custard before the nutmeg.
After pre-baking the pastry shell before adding the sliced fruit filling, spread on a thin layer of preserves to help seal the crust bottom to prevent sogginess. Whereas vegetables, as long as they're well dried, don't tend to affect the crispness of a custard tart's crust, moist fruit with a high water content may cause sogginess. The layer of fruit preserves should be thin and not extremely high in sugar or it may not seal the tart shell well.
Using fresh large eggs in a custard savory or dessert tart is important, as the eggs are what sets the consistency of the filling. It's best to never freeze custard tarts because of their high egg content. Typically, custard tart recipes call for about four eggs and the flavor and texture after freezing these dishes is often of poor quality. Jam tarts tend to freeze extremely well as they lack the egg-based, custard filling.