As their name indicates, the circles are simple circles, made of stainless steel, which exist in different diameters, but unlike a mould, a circle has no bottom (yes, this is not an extraordinary statement) so it must be placed on a baking sheet, protected by a sheet of baking paper, or silicone (silpat), before baking.
Before continuing, just 2 words of baker's vocabulary :
-"
rolled-out pastry": Piece of dough that is rolled out and used to line a mould/circle
-"
line (with pastry)": Action of lining a mould/circle with an abaisse
So on one side we have the classic pie tin, which you put in the oven directly or on a baking sheet, and on the other side the circle, which must be placed on a baking sheet.
Which is better?
The circle has many advantages:
- The baking is better, more regular and faster because of the absence of a bottom, more direct contact of the pastry with the heat
- Unmoulding is very easy, you just have to remove the circle from the top and then slide the tart into its serving dish (breaking a tart when taking it out of its mould is a very very frustrating moment!)
- It is very easy to clean, dishwasher safe
- If you go for it carefully, you'll get very elegant and professional right-angled pie edges
- It costs less than a mould
As you can see, it's almost all advantages, that's why pro pastry chefs all use circles, and you can do the same at home.
There is only one case, where the mould is preferable, and that is if you are making a quiche, or a tart with a lot of cooking juice, like a
tomato tart, or a fresh plum or blackberry tart for example, in these cases having a mould (rather than a circle) that will retain the cooking juice even if you have a leak in your pastry case is very appreciable.
I didn't go into detail, but as for the moulds, there are circles for tarts, of all sizes in fact, and square or rectangular shapes, the pastry cooks speak then rather of "frames".
Another quite recent option, the circles are said to be micro-perforated, i.e. pierced with hundreds of small holes that improve the baking process by distributing the heat better.
As always for the material, do not hesitate to put the price, it is an investment on the duration, and to go to provide you in the stores for professionals rather than in the ray kitchen of the great surfaces.
To sum up: Try the circles instead of the pie tins, once you get the hang of it, you will appreciate the difference.