To blind bake a pie crust means to partially or completely bake the pie crust before filling it.
Blind baking, also known as pre-baking, serves a number of purposes. First, you might want to blind bake a pie crust when the pie filling takes less time to cook than the crust itself.
Secondly, you would blind bake a crust when making a cream pie or chiffon pie, because those types of pies are not baked at all.
Blind baking also helps to prevent a soggy bottom crust when making fruit pies. Blind baking is used for making tart shells as well as pies.
When blind baking, the pie crust is lined with parchment paper and then filled with uncooked beans or rice, and then baked. This prevents the crust from puffing up while it bakes. After baking, the beans or rice are removed and the pie crust is filled. You can also buy special pie weights that work the same way as the beans.