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A crumb crust is a classic choice in many single-crust pies. It’s more durable than classic pie dough, making it the right choice for the moist custard-based fillings in recipes like Key Lime Pie (recipe below).
Graham crackers are the classic choice. For chocolate cookie crusts, we prefer Oreos. While buying a store-bought ready-to-go crust is a tempting shortcut, these are always stale and bland. Making your own is incredibly easy and well worth it for a fresh-tasting crust with a crisp texture and balanced sweetness to do your homemade pie filling justice.
1. Grind crumbs
Why? The metal blade of a food processor turns hard crackers or cookies into even crumbs in seconds. It’s also the best way to incorporate the sugar (a must with graham crackers, but unnecessary with sweeter cookies) and melted butter. Since sandwich cookies are heftier than graham crackers, it’s best to break them up before processing.
2. Shape into crust
Why? The butter moistens the crumbs, but a little elbow grease is required to create a cohesive crust. Make sure to build the crust up the sides of the pie plate. A dry measuring cup (the 1/3 or 1/2 cup measure in most sets works best) keeps your hands clean and allows you to create an even, firmly packed surface.
3. Bake until fragrant and just browning
Why? Many recipes skip the prebaking step, but this is a big mistake. Baking the crumbs makes the crust cohesive and gives mild graham crackers a nice toasty flavor.
Q: I want to use store-bought graham cracker crumbs.
A: In theory, these crumbs would work in our recipe, but we have found that they are often quite stale. And they don’t save you much time, since you still need to add sugar and melted butter. We strongly recommend you take 30 seconds to grind your own crumbs.
Q: Can I just use a store-bought graham cracker crust?
A: Please don’t! We tasted three leading brands and were shocked at their bland, artificial flavor and sandy, crumbly texture. Commercial crusts are made with shortening, not butter, and you can taste the difference. Also, these crusts aren’t sufficiently baked. The 5 minutes of hands-on work needed to make your own crumb crust is time well spent.
Q: I can’t tell if the crust is done baking.
A: While you can easily use color change to judge when pie dough is baked, it’s pretty difficult to tell when a crumb crust is done, at least with just your eyes. The crust should be fragrant (but not burned) and firm to the touch. If the crust feels soft or not quite set, give it a few more minutes in the oven.
Q: Can I use chocolate wafer cookies instead of Oreos for a chocolate crust?
A: We wouldn’t recommend it. Chocolate wafer cookies are the more conventional choice for this type of crust, but we have found that they taste bland and tough. Because of the richness of the Oreo filling, the crust is guaranteed to be tender.
Key Lime Pie
Why this recipe works
Traditional Key lime pie is usually not baked; instead, the combination of egg yolks, lime juice, and sweetened condensed milk firms up when chilled because the juice’s acidity causes the proteins in the eggs and milk to bind. We found that just one simple swap—from bottled, reconstituted lime juice to juice and zest from fresh limes—gave us a pie that was pungent and refreshing, cool yet creamy, and very satisfying.
We also discovered that while the pie filling will set without baking (most recipes call only for mixing and then chilling), it set much more nicely after being baked for only 15 minutes. We tried more dramatic departures from the “classic” recipe—folding in egg whites, substituting heavy cream for condensed milk—but they didn’t work. Just two seemingly minor adjustments to the classic recipe made all the difference.
Despite this pie’s name, we found that most tasters could not tell the difference between pies made with regular supermarket limes (called Persian limes) and true Key limes. Since Persian limes are easier to find and juice, we recommend them.
The timing here is different from other pies; you need to make the filling first, then prepare the crust. We don’t recommend using store-bought graham cracker crumbs here as they can often be stale.
Graham Cracker Crust
1. FOR THE PIE: Whisk egg yolks and lime zest together in medium bowl until mixture has light green tint, about 2 minutes. Whisk in condensed milk until smooth, then whisk in lime juice. Cover mixture and set aside at room temperature until thickened, about 30 minutes.
2. Meanwhile, prepare and bake crust. Adjust oven rack to middle position and heat oven to 325 degrees. Process graham cracker pieces in food processor to fine, even crumbs, about 30 seconds. Sprinkle melted butter and sugar over crumbs and pulse to incorporate, about 5 pulses.
3. Sprinkle mixture into 9-inch pie plate. Using bottom of dry measuring cup, press crumbs into even layer on bottom and sides of pie plate. Bake until crust is fragrant and beginning to brown, 13 to 18 minutes; transfer to wire rack and leave oven at 325 degrees. (Crust must still be warm when filling is added.)
4. Pour thickened filling into warm prebaked pie crust. Bake pie until center is firm but jiggles slightly when shaken, 15 to 20 minutes. Let pie cool slightly on wire rack, about 1 hour, then cover loosely with plastic wrap and refrigerate until filling is chilled and set, about 3 hours.
5. FOR THE TOPPING, IF USING: Once pie is chilled, use stand mixer fitted with whisk to whip cream and sugar on medium-low speed until foamy, about 1 minute. Increase speed to high and whip until soft peaks form, 1 to 3 minutes. Spread whipped cream attractively over top of pie. Serve.
This pie tutorial and recipe are from the America's Test Kitchen Cooking School Cookbook. With 832 pages, 600 recipes, and 2,500 photos, it has everything you need to become a great cook.