Key Lime Pie

No doubt the simplicity of key lime pie contributed to its popularity. There is something inherently appealing about it, probably the contrast in texture between crumb crust and smooth filling; the juxtaposed flavors of sweet custard and tart lime juice. It’s become a restaurant cliché but more often than not what will be set before you came frozen from a wholesale food purveyor. Go figure since traditional key lime pie couldn’t be easier to concoct: a graham cracker crust with a filling made from eggs, sweetened condensed milk and lime juice and zest. (The Continental in Fitchburg serves a traditional key lime pie and Restaurant Magnus an exotic modern rendition, both homemade.)

Gale Borden, founder of the soon-to-be-famous Borden Milk Company developed sweetened condensed milk in 1856. Prior to the advent of refrigeration, milk was a difficult staple to have on hand, especially during warm weather. Borden figured out a process where he could take fresh milk, heat it, remove the water and sweetened it with sugar (to improve the taste). The end result was thick, sweet and when canned keep unrefrigerated for years. Originally, the product—marketed as Eagle Brand Milk—was diluted with water to make a palatable drink but also was used straight from the can as a coffee creamer.

Sweetened condensed milk became popular during the American Civil War when the government bought huge quantities and included it as part of the field rations. After iceboxes and then refrigerators became ubiquitous, the sales of condensed milk declined. In 1931, the Borden Company started offering $25 (a heap of money during the Depression) for original recipes that they would print on the label. Considering the nature of the product, many of these recipes were for desserts. One of these recipes, lemon icebox pie, became all the rage. Simple to make, it was also a novelty at the time since it wasn’t baked but instead the filling miraculously thickened in the icebox.

Today sweetened condensed milk and condensed milk are one and the same. The unsweetened version is now marketed as evaporated milk.

Nobody knows who made the first key lime pie but it’s definitely a Florida variation of lemon icebox pie, using the tart limes that use to grow in abundance in the Keys. Key limes (also called West Indian or Mexican limes) are small, seedy and yellowish when ripe. More common is the larger, seedless, dark green Persian lime (also called Tahitian or Bearss lime).

Today, even in Florida most key lime pies are made using Persian limes. In 1926 a hurricane wiped out most of the key lime trees in Southern Florida. When commercial growers replanted they opted for the heartier Persian variety. Ironically now you will find nary a key lime even in Key West unless it came from Texas or Mexico.

My first key lime pie experience was in 1957 at a famous deli in Sunny Isles Beach called Wolfie Cohen’s Rascal House. Sadly this Miami institution closed this past March. The Rascal House served all the classics that you’d expect to find at a Jewish delicatessen; all in copious portions. Most notable, though, was the key lime pie topped with a foot of meringue.

Originally, key lime pie was always crowned with meringue which today is usually replaced with whipped cream. Meringue after all takes some finesse by the cook to make and doesn’t hold up well – it’s prone to shrink and weep. I actually think whipped cream is an improvement on the original recipe since meringue tends to make this pie cloyingly sweet.

Rather than offer a recipe for traditional key lime pie since you can find them everywhere, here is my recipe for (uff da!) Wisconsin Lime Pie. We may not grow any limes but, we got dairy, you betcha!

Wisconsin Lime Pie

1 9-inch crumb crust, made from graham crackers or Nikki’s Key Lime Shortbread Cookies

1 cup granulated sugar
3 tablespoons cornstarch
4 tablespoons unsalted butter
1 tablespoon finely grated lime zest
1/3 cup fresh lime juice
1 cup light cream (half-n-half)
1 cup sour cream
Combine the sugar, cornstarch, butter, lime zest and juice, and light cream in a saucepan. Bring to a boil over medium heat, stirring constantly. Cook until thickened and smooth. Remove from the heat and let the mixture cool completely.

Fold in the sour cream. Pour the mixture into the crumb crust, cover with plastic wrap and chill while making the Whipped Cream Topping.

Spread the Whipped Cream Topping over the pie and chill for 2 hours or until serving time. (It’s best if made the day it is to be served.)

Serves 6 to 8.

Whipped Cream Topping:
2 cups heavy cream
2 tablespoons cold water
2 teaspoons unflavored gelatin
1 tablespoon confectioners’ sugar
1 teaspoon vanilla extract

Put the cold water in a small glass measuring cup and sprinkle with gelatin. Let the mixture soften for about 5 minutes.

In a chilled bowl beat the cream, confectioner's sugar and vanilla until it just holds its shape.

Melt the softened gelatin in the measuring cup in the microwave for 15 seconds and let cool slightly. Beating constantly, add the liquid gelatin to the whipped cream. Continue beating just until the gelatin is well combined.