Cookbook:Crumb Crust

A crumb crust is a variety of pastry crust made primarily of cracker or crispy cookie crumbs.

Characteristics
The crust base is made by grinding cookies or crackers, binding them with melted fat and sugar, and pressing them into a mold or pan. It may also be baked, which adds extra crispness and depth of flavor. Any kind of crisp cracker or cookie can be used—common ones include graham crackers, oreos, shortbread, wafers, pretzels, digestives, and gingersnaps. Ground nuts can also be included to an extent. Additionally, because gluten development is not required for texture, crumb crusts are easy to make gluten-free without significant differences.

Technique
When grinding the crumbs, you want to make sure that the cookies/crackers are very crispy and that the end result is very fine and sandy. Chewy cookies and larger lumps will prevent the crust from holding together. Work in just enough melted fat (e.g. butter, coconut oil) to moisten the crumbs and enable them to hold together when squeezed—the exact amount will depend on the properties of your crumbs. Work in a dash of sugar as well, which will help bind the mixture. When pressing the mixture into the mold, it's a good idea to use a sturdy cup of some kind to get it well compacted all across the bottom and up the sides—using your fingers can cause unevenness and a weak structure. If you will be parbaking the crust, bake for about 8–15 minutes at 350°F/180°C, or until it is light golden, aromatic, and slightly dry in texture. You don't necessarily have to bake the crust, but it helps it resist very moist fillings.

Selection and storage
Choose your variety of crust according to your filling. You may want the flavors to be complementary (e.g. chocolate crust and filling) or contrasting (e.g. salty crust with sweet filling). Crumb crusts store quite well. You can keep it wrapped at room temperature for a day or two, and it keeps well in the freezer for longer-term storage.

Use
Crumb crusts can be used for a variety of pies, bars, cheesecakes, and other pastries. They work best with custard-based fillings, such as pumpkin, key lime, and cheesecake, which have their own structure and whose smoothness pairs well with the crumble of the crust. Unfortunately, crumb crusts don't work with a lot of fruit pies (e.g. apple, blueberry), since they're not sturdy enough to withstand the high moisture and low structure of these fillings. They also are not suitable for applications where the exposed crust will be baked for over ~25 minutes, since this is likely to burn it.