Add the lime juice once you've fully cooked the custard to let the cornstarch thicken the mixture properly.
3/4 cup granulated sugar
1/4 cup cornstarch
1/8 teaspoon kosher salt
4 large egg yolks
2 cups half-and-half
3 tablespoons butter
2 tablespoons Key lime zest*
1/2 cup fresh Key lime juice*
45 graham cracker squares
1 cup whipping cream
1/4 cup powdered sugar
How to Make It
Whisk together first 3 ingredients in a heavy saucepan. Whisk together egg yolks and half-and-half in a bowl. Gradually whisk egg mixture into sugar mixture; bring to a boil over medium heat, whisking constantly. Boil, whisking constantly, 1 minute; remove from heat. Whisk in butter and zest until butter melts. Gradually whisk in juice just until blended. Pour into a metal bowl, and place bowl on ice. Let stand, stirring occasionally, 8 to 10 minutes or until custard is cold and slightly thickened.
Meanwhile, line bottom and sides of an 8-inch square pan with plastic wrap, allowing 4 inches to extend over sides. Place 9 graham crackers, with sides touching, in a single layer in bottom of pan to form a large square. (Crackers will not completely cover bottom.)
Spoon about 3/4 cup cold custard over crackers; spread to edge of crackers. Repeat layers 3 times with crackers and remaining custard, ending with custard; top with remaining 9 crackers. Pull sides of plastic wrap tightly over cake; freeze in pan 8 hours.
Lift cake from pan, and place on a platter; discard plastic wrap. Cover loosely; let stand 1 hour.
Beat whipping cream at high speed with an electric mixer until foamy; gradually add powdered sugar, beating until soft peaks form. Spread on top of cake.
*Regular (Persian) lime zest and juice may be substituted.
I used bottled Persian lime juice and no zest. Crackers fit well in the 8" pan. I lined pan with plastic and wrapped it around the cake for easy removal. I found there was enough filling when it was not used on the top layer of crackers - just as recipe instructs. I like that it was not overly sweet like some key lime recipes, perhaps due to using the Persian lime juice. Everyone loved the cake as one of our desserts for Thanksgiving meal. Cake was just as good after being in the freezer for several days. Great recipe to make in advance.
I made this recipe for a luncheon at work. I agree that the top layer of graham crackers is not needed. I used Cool Whip for the topping instead of the homemade whipped cream because I was afraid it wouldn't stand up sitting out so long but if making it at home would definitely use the whipped cream. Everything fit in an 8" square pan and I refrigerated it overnight instead of putting it in the freezer. There was plenty of filling but if I made it again I would probably use a regular key lime pie filling of sweetened condensed milk, key lime juice and egg yolks. It was a lot of work zesting and juicing almost a whole bag of key limes to get the recommended amounts listed in the recipe. It was good but I prefer regular key lime pie.
There is not enough filling for the number of graham crackers. This was very dry and not at all flavorful. Perhaps using fewer crackers would improve the recipe. Graham crackers are certainly not needed on the top.
I had to use a 9" square pan to get 9 graham cracker squares per layer. An 8" square pan would not work. Also, I only had enough custard to make 4 layers so I only needed 36 crackers instead of 45. I was a bit disappointed in the final outcome considering the prep work needed to complete the final recipe.
I'm not sure what people spazzed out about. I bought regular graham crackers that came in squares - nine squares per layer in an eight inch dish. It fit perfectly.
The taste is incredible - like a Lime Icebox Pie. I think the only thing I would change, next time, is refrigerate, instead of freeze, because it is great as a regular pie, rather than an ice cream pie.
Regardless - it's pretty darn scrumptious!
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