Q: When does a pastry case need to be blind baked before the filling is added?
A: I love this question as it is a really common one.
Blind baking is when you bake the pastry case in two stages without the filling and the purpose of it is so that filling doesn’t make the pastry soggy (and it remains flaky and crisp), and there is a clear distinction between the filling and the pastry
It is a technique that needs to be used when making a tart or pie that has a wet filling. Lemon tarts and quiches are good examples of these as they are made with custard fillings.
When blind baking, the first stage the pastry is weighed down by pastry weights or dried rice during baking to help keep its shape. And then the weights are removed, and the pastry is baked further until the pastry is sealed and dry on the surface.
You then add the filling and continue to bake. I find that adding the filling while the pastry case is still hot is the best way to also help stop the pastry form absorbing the wet filling as it starts to set as soon as it comes in contact with the pastry, creating a natural seal.