I discovered this recipe when a friend made it a few years ago. When I asked for it, I was given a photocopy of the hand-written index card. It really is super simple, and just as tasty as a Key Lime Pie. For those of us with acid issues, the extra Graham Crackers help a great deal in cutting the acidic lime juice.

Icebox Cakes can really be made with any custard and any cookie or Graham Crackers, and they are a great dessert for those days when you have absolutely no desire to turn on the oven (you know, days when the heat index is 119 degrees).

For a great garnish, try making some candied lime slices for each slice of the Icebox Cake, I am including a recipe for those as well.

While this recipe uses no special tools, a square springform pan is great.

Whisk together first 3 ingredients in a heavy saucepan.

Whisk together egg yolks and half-and-half in a bowl.

Temper the egg yolk mixture before adding slowly to the remaining sugar mixture; bring to a boil over medium heat, whisking constantly.

Boil, whisking constantly, 1 minute and remove from heat.

Beat in butter and zest until butter melts.

Gradually stir in juice just until incorporated. Pour into a heatproof bowl, and place bowl in an ice bath. Let stand, stirring occasionally, 8 to 10 minutes or until custard is cold and thickens slightly.

Line bottom and sides of an 8-inch square pan with plastic wrap, allowing 4 inches to extend over sides (you may need two sheets if you are not using wide plastic wrap). Place 9 graham crackers, with just the slightest bit of space between each, in a single layer in bottom of pan to form a large square. The crackers will not completely cover bottom.

Spoon about 1/3 of the cold custard over crackers; spread to edge of crackers. Repeat layers 3 times with crackers custard, with the last layer being custard; top with remaining 9 crackers. Pull sides of plastic wrap tightly over cake. Wrap entire pan tightly with plastic wrap and freeze in pan at least 8 hours.

Remove outer layer of plastic wrap, remove overlapping plastic wrap from top of cake and invert cake a platter; discard inner layer of plastic wrap. Cover loosely; let stand 1 hour.

Top cake with cream whipped to soft peaks with the powdered sugar.

Candied Lime Slices

Set up an ice bath and a wire rack set over a baking sheet lined parchment paper. Spray baking sheet lightly with cooking spray.

Using a mandolin or very sharp knife, cut limes into ⅛-inch slices. Discard seeds and the ends.

Add water to a saucepan and bring to a boil over high heat. Remove from heat and add lime slices, stir gently until they are softened, about 1 minute. Remove lime slices from water and quickly transfer to ice bath.

Add sugar and 1 cup of water to a saucepan and bring to a boil over medium-high heat. You may need to stir gently to dissolve sugar. When mixture begins to boil, reduce heat to a simmer add lime slices, in a single layer. Simmer gently until rinds are translucent, this will take 45 to 60 minutes.

Carefully transfer lime slices to the wire rack to cool and set for at least 1 hour or until the slices are no longer sticky and have hardened slightly.