Icebox cakes are an excellent summertime dessert because they require no baking – and, thus, don’t heat up your kitchen – and they are served cold, which makes them a delightfully cool treat on a hot afternoon. These “cakes” aren’t really cakes at all. Icebox cakes are layered desserts that typically have a cookie or graham cracker base to give it structure, since they’re not put together like traditional cakes. The cookies are surrounded with some type of filling, which softens the cookies and gives the dessert its flavor.
This Lemonade Icebox Cake is a great example of an icebox cake and it is inspired by the flavor of fresh lemonade, one of my favorite summer drinks. It starts with a lot of graham crackers and a homemade lemon custard that is full of fresh lemon juice and zest. These elements are stacked into a “cake” that is five layers high, making it a pretty impressive looking dessert when you are ready to serve it. Although the cake is not baked, it does require a little bit of cooking. The lemon custard is cooked on the stove top and it is thickened with both eggs and cornstarch to give it a thick, creamy texture that is needed to build the layers of this cake. It has just the right amount of sweetness to balance out the zesty lemon juice, but it is just tart enough that the dessert ends up being very refreshing and not cloying.
The hint of honey and brown sugar from the graham crackers goes very well with the bright lemon filling, adding a little extra sweetness behind the fresh lemon flavor. For me, the whipped cream on top is a must-have when you are serving this, since it not only gives each slice a lovely finished look, but it helps to bind the elements of the cake together a little bit more. I like to eat the cake when it is still very cold and it has a firmer texture, but if you like your frozen desserts a little softer, you can let your cake sit out for 20-30 minutes before slicing it. Since this dessert must be stored in the freezer, I recommend slicing it up the first time that you take it out of the pan, then return all the extra slices to the freezer for later use. You can pop them into the pan or wrap them individually for single-servings later.
Lemonade Icebox Cake
3/4 cup + 2 tbsp sugar
1/4 cup cornstarch
1/8 tsp salt
4 large egg yolks
1 cup heavy cream
1 cup milk
2 tbsp butter
1 tbsp lemon zest
1/2 cup lemon juice, freshly squeezed
1/2 tsp vanilla extract
1/4 tsp lemon extract (optional)
45 graham cracker squares
lightly sweetened whipped cream, to serve
In a medium saucepan, combine all of the sugar, cornstarch and salt and whisk to combine.
In a medium bowl or large measuring cup, whisk together egg yolks, cream and milk. Pour into the saucepan with the sugar and whisk to combine. Cook mixture over medium heat, whisking continuously, and bring to a boil. When mixture boils, remove from heat immediately. Whisk in butter and lemon zest, stirring until the butter is completely incorporated. Whisk in lemon juice, vanilla extract and lemon extract (if using) until mixture is very smooth.
Transfer to a clean bowl and cool over an ice bath or cover with plastic wrap and refrigerate until cold.
Line an 8-inch square baking pan with plastic wrap, leaving 6-8 inches of plastic wrap extending over all sides of the pan.
Place 9 graham cracker squares over the base of the pan. Top graham layer with 3/4 cup lemon custard and spread custard into a thin, even layer. Top with second layer of 9 graham cracker squares. Repeat with lemon custard and remaining graham crackers until you have four layers of custard and have used all of it. Top with a final layer of 9 graham crackers.
Pull the plastic wrap tightly over the cake and freeze overnight.
When ready to serve, lift the cake out and unwrap it on a serving platter. Allow it to soften for 5-10 minutes, then slice with a sharp knife. Top each piece with a dollop of whipped cream to serve.