From: U.S.A. Cookbook by Sheila Lukins (Workman Publishing, 1997), pp. 517-518
A visit to the Florida Keys is synonymous with eating Key lime pie. It's so smooth and refreshing, and while everyone seems to have their own delicious version, sweetened condensed milk is a universal ingredient. Key limes are grown in southern Florida and have a very thin, greenish-yellow peel; the juice is tangier and more intense than a regular lime. If you cannot find fresh Key limes, the juice is available, sold in bottles, in specialty food stores and fine supermarkets. Regular lime juice just doesn't give the same pucker, and is not a good substitute. Be sure to chill the pie thoroughly before serving so that the fill sets up nicely.
Serves 6 to 8.
1 1/4 cups graham cracker crumbs (about eleven 5 x 2 1/2-inch crackers)
1/4 cup granulated sugar
1/3 cup unsalted butter, melted
4 large egg yolks
1 can (14 ounces) sweetened condensed milk
1/2 cup Key lime juice [I tend to put more like 3/4 cup because I like it tart, but watch it; don't want to go overboard)
1 cup heavy (or whipping) cream
1/4 cup confectioners' sugar
Thin lime slices, for garnish
1. Preheat the oven to 350 F.
2. Prepare the crust: Combine the graham cracker crumbs, sugar, and melted butter in a small bowl and mix well. Press the mixture evenly over the bottom and sides of a 9-inch pie plate. Bake in the center of the oven for 8 minutes, then cool completely on a rack.
3. Prepare the filling: Beat the egg yolks in a medium-size bowl with an electric mixer at medium speed until light. Add the sweetened condensed milk and the Key lime juice and beat until well blended. Pour the filling into the prepared crust and bake the pie in the center of the oven until the filling is set but still creamy, about 15 minutes. Cool the pie completely on a rack and then chill thoroughly in the refrigerator for at least 4 hours.
4. Prepare the topping: Before serving, whip the cream with the confectioners' sugar until it holds firm peaks. Use a rubber spatula to swirl it over the surface of the pie, or use a pastry bag to pipe it decoratively. Decorate the cream with the lime slices and return the pie to the refrigerator until serving time.
Personal Note: This recipe never steers me wrong, though it's ambiguous in many places. Since it is, I'll add some notes I've accumulated from making this multiple times. For one thing, I think this recipe downplays just how many machines are at work. The hands down best and (as counter-intuitive as it seems due to the hassle and mess of the parts) easiest way to crumble the graham crackers is with a standard food processor. Really mix the crust ingredients together thoroughly so the butter and sugar permeate the cracker crumbs evenly. You'll also need an electric mixer, which is mentioned in the recipe; I don't bother with the Kitchenaid and just use one of those cheapo hand-held batter beaters to beat the yolks (when they say "light," they likely mean both in color and texture--I always wait until the yolks turn pale and are almost airy, and it seems to work well) and blend the filling ingredients. For best results, you'll also need a hand-held immersion blender, like the standard Braun model, to whip the cream topping at the end. The hands down easiest mistake to make with this pie, and one severe enough to really ruin the visual and textural effect, is not letting it cool completely, both during the crust baking step and the filling step. Let it get REALLY cool on a rack (and in the case of the topping, wait indeed until the filling's been refrigerated for 4 hours), because if you don't, when you pour the filling or whipped topping on the hot baked surface, the filling or whipped topping will bubble, become watery, and run. And especially with the whipped topping, after this happens it will not right itself with chilling in the fridge, and you will have a permanently liquid, if edible, mess. The other trick to making sure the whipped topping really seems like whipped topping--not creamy water but thick and airy like Cool Whip only better--is to thoroughly use the immersion blender and be patient. Whip the hell out of it until it's thick and the immersion blender blades slow. If you can't handle the idea of messing around (fuss wise or calorie wise) with real whipped cream topping, Cool Whip is of course an option. But the real topping is out of this world, and licking the spatula is a bit of heaven.
Remember to be sanitary about raw egg--don't use the same spatula you used to scrape the raw filling from the mixing bowl to the pie crust to later scrape whipped cream, just basic reminder stuff like that.
When the pie's chilling in the fridge for the 4+ hours, I don't cover it with anything (plastic wrap or whatnot). But then, I chill it in the beverage fridge usually, so there's no risk of nasty or clashing food smells/flavors infiltrating the pie.
Key limes generally are way too expensive to waste making juice from; we buy a bottle of the juice from Wegman's in the baking aisle. A single bottle, about 2 bucks, has enough juice for about 3 or 4 pies.
As a random side note, damn do I love sweetened condensed milk. I always lick the can. It's one of my "weird/icky but oh so tasty" guilty pleasures, along with frozen bananas, unsalted pretzels, plain matzo, bisquick mix straight up, tuna fish sandwiches with potato chips crunched into them, special k flakes mixed into yoplait or crowley yogurt, coconut milk, dry breadsticks, cheap/minute rice with shredded cheese melted over it, banana slices with rice pudding, etc etc. Yes, I am kind of gross. :b I should get one of those t shirts that says "I heart CARBS" on it, har.