Andy M. said:
Brush the bottom crust with some egg white and bake it in a hot oven for a few minutes to set it.
andy m. - what with you being a mod and having so many posts, etc. i'm a little leary of saying this, but do you actually do this? how does it come out?
popping the bottom crust into a hot oven for a few minutes will melt all the shortening, after which you're going to pull it out of the oven and let it cool again. and then attach the top crust to a partially baked bottom? how many is a few minutes. the crust by itself would be completely cooked in between 10 - 15 depending on how hot of an oven you're talking about. if you've done this and the results are good, then someday i may give it a shot with say a pumpkin pie.
actually, you can get a bottom crust that is actually crispy*(see below, where i 'fess up) by paying attention to a few details. unlike my cake pans, i keep my pie pans well seasoned: read quite dark. it conducts the heat faster. grease the pie pan before putting in the bottom crust. go ahead and slice your apples first if you want, but have your oven preheated by this point to about 400 or 425 degrees f. and have both the top and bottom crusts ready before you add the sugar, spices, flour or tapioca etc. if you do this first, the apples and sugar will start producing juices the whole time you're preparing your crust. when all is ready, add the sugar, spices, etc, to the apples, give a quick toss to just coat all the apples, get them into the pie, place top crust on, seal, flute, brush with an egg wash, cut a vent and pop it into the oven with alacrity. bake at high heat for about 10 minutes and then reduce the temp. to 350 or whatever you're recipe calls for and bake for another 40 minutes, either more or less depending on how many apples you've got packed in there and whether you like them crispy or well cooked and soft.
as for the crust, i go with the old-school 3-2-1 ratio, although i eyeball the water. 2 parts butter to 3 parts flour is rather high on the shortening side compared to many pie crust recipes i've seen posted, but for a flakey top and crispy bottom, lesser ratios are a compromise. the down-side to this ratio is oven clean up, because a certain amount of the butter will drip.
and now for the crispy* confession, for which i may get roasted (hee hee). well, of course there's no way to achieve a bottom crust every bit as flakey and crispy as the top. to qualify what i mean by crispy, on an apple pie, about 1/2 to 2/3 of the bottom crust can come out crispy; on a pumpkin or berry pie about only about 1/3 to 1/2.