Graham cracker crusts are more foolproof than regular piecrusts, but they can crumble. The most common reason a crust crumbles is that it wasn't moist enough. Be sure to use melted butter, egg whites or oil to moisten the crumbs. Butter gives the best flavor, but a mild-flavored olive oil or vegetable oil is healthier.
Bind It Up
Adding a beaten egg white to the crumb mixture can help prevent crumbling because the protein in the egg white binds the crumbs together. Adding an egg white also means you can use less melted butter for a healthier crust. Combine the egg white with the graham crackers, sugar and melted butter in a food processor and pulse for just a few seconds or until the crumbs are thoroughly moistened. Be sure to cook the crust in the oven for several minutes -- not only to firm it up, but also to destroy any bacteria in the egg white.
Choose Your Pan
The pan you choose for your piecrust can also make a difference in how well it holds up. Opt for a shallow glass or ceramic pan without deeply sloped sides or fluted edges. Graham cracker crusts tend to slump and crack in these pans. For bars, spread the crust over the bottom of a baking pan only -- not up the sides.
Press It Down
Forget using your fingertips to press a graham cracker crust into a pie pan. It's almost impossible to get the crust even with this method or compact enough that it doesn't crack. Use the bottom of a glass or cup instead. First, spray the pie pan or baking sheet with a bit of non-stick cooking spray. Add the crumbs and press them down firmly with the glass. With this method, you can get into the corners and create a firm, stable crust.
Fill It Up
Now for the best part -- the filling. Spread the custard, pudding or other filling evenly over the graham cracker crust. Cover and refrigerate the dessert for at least two hours. This chilling time allows the filling to set with the crust so it's less likely to crumble when you cut it. Use a sharp knife and a pie spatula to make neat cuts. Wipe your knife on a paper towel between cuts.