The best way to keep the bottom crust of the apple pie from getting soggy is to cook the bottom crust faster so that it cooks faster than the rest of the pie. There are many ways to this. One of the most foolproof ways is to preheat the oven with a baking sheet placed on a rack at the bottom third of oven and bake the pie directly on the heated baking sheet. Other popular ways include blind baking before assembling the pie and sprinkling dried breadcrumbs or crumbled cereal at the bottom of the crust to absorb excess liquid prior to pouring in the filling.