The 4 types of pies are.
Open-face pies only have a bottom crust and are typically sweet.
Double-crust pies have a bottom crust and a top crust.
Lattice pies have a bottom crust and decorative top crust made with strips of dough.
Deep-dish pies do not have a bottom crust—just a single crust on the top.
A crustless pie also called a deep dish pie is a pie with no bottom crust which can be any type of pie without the bottom crust.
A pie with no bottom crust is just simply called a crustless pie.
Even though the pie has no bottom crust it's still a pie but just a crustless pie.
The lack of crust might not make much of a difference for a pumpkin or a pecan pie, but when it comes to the classic fruit pies — apple, blueberry, cherry, peach — no crust just seems wrong.
Think about it. How is a crustless apple pie any different from sautéed apples? Here's how.
The popular crustless pie recipes like this Crustless Blueberry Pie don't forgo many of the ingredients in a classic pie crust, they just use them differently.
Instead of making a crust with flour they mix flour with eggs and butter and pour the mixture over the fruit and sugar.
If you're looking for the miracle of a gluten-free pie sans crust, this isn't that miracle (unless you substitute gluten-free flour for white flour).
The end result is something more in line with a clafoutis than a pie.
The fruit ends up embedded in a cake-like base.
The main difference I see between crustless pies and a clafoutis is that a clafoutis adds some milk to the mix to make the inside a bit more custard-like.
Most people if given the choice would choose a traditional fruit pie with crust over one of these crustless pies, but I can see where a crustless pie makes sense.
If you don't have any pre-made crusts, and you don't want to take the time to make crust (or you aren't confident in your crust-making abilities), you can whip up a crustless pie quickly.