A few weeks ago our family was in Panama City, Florida visiting my parents. After a playful day at the beach, we ended up in the Saint Andrew’s section of town at a restaurant called Uncle Ernie’s, a converted old house that sits on a dock right over the bay. Sun-drained and pink-skinned we washed down gulf seafood with a pitcher of beer and watched a stunning sunset.
At the end of the meal our waiter tempted us with dessert. He strongly suggested Earnie’s house-made key lime pie. We took the bait. Their pie was classically made, and its dense jiggly texture and intensely tart-sweet flavor took me back a dozen years when I was working on key lime pie for my third book, CookSmart. I hadn’t made this pie in a while, and tasting Uncle Earnie’s made me want to try mine again. So I did.
Back then, the goal for my key lime pie was to develop one that was “pleasantly, not puckery tart, and perfectly, not treakly sweet.” I also wanted to “lighten the pie without turning it into a mousse or soufflé.”
To ever so lightly lighten the pie (and simultaneously tone down the sweetness) I added just one whipped egg white to the lime juice-condensed milk mixture. Any more and it morphed into mousse. The one whipped egg white worked, but not for long. As the pie sat, the egg white in this pie did what all whipped egg whites eventually do. It deflated and returned to its liquid state causing the pie to weep. In my previous attempts to perfect lemon meringue pie I knew what to do. I cooked up a cornstarch slurry to stabilize the meringue. It worked.
Since most key lime pies are either not baked or baked for only fifteen minutes, the yolks don’t reach a safe temperature, so for those who want a totally safe pie, I did one other thing. I carefully heated the yolks and condensed milk to a safe temperature before baking it. If this is not an issue for you, simply mix the egg yolks and condensed milk and then whisk in the lime juice just before folding in the beaten egg white.
Not long after our Uncle Ernie’s dinner, I served my pie to Sharon. Her response: “Now that’s perfect key lime pie.”
Light, Just Right Key Lime Pie
1 1/4 cups graham cracker crumbs (11 whole if using crackers) or zwieback crumbs (15 toasts)
3 tablespoons, plus 2 teaspoons sugar, divided
5 tablespoons butter, melted
4 egg yolks, saving 1 egg white
1 can sweetened condensed milk, preferably Carnation brand
1 tablespoon cornstarch
10 tablespoons lime juice and 1/2 teaspoon lime zest from 4 limes
1/8 teaspoon salt
Adjust oven rack to lower middle position and heat oven to 325 degrees. Mix crumbs and 3 tablespoons of sugar in a medium bowl. Add butter and stir with a fork until well incorporated. Dump crumbs into a 9-inch pie plate and spread evenly over bottom. Tamp crumbs down over pan bottom and up the sides. Bake until fragrant, about 15 minutes. Remove from oven and set aside and reduce oven temperature to 300 degrees.
Whisking constantly, heat yolks and half the condensed milk in a small saucepan over low heat until it reaches 160 degrees. To keep eggs from curdling, immediately pour mixture into a medium bowl and stir in remaining condensed milk. Set aside.
Whisking constantly, heat cornstarch and 1/3 cup water in a small saucepan over low heat until clear and thick, 2 to 3 minutes. Remove from heat. Meanwhile, beat egg white over medium speed until foamy. Gradually adding sugar, beat white until glossy and soft peaks form. Add half the thickened cornstarch to the white and beat until just incorporated. Discard remaining thickened cornstarch.
Mix lime juice, zest, and salt, then beat into the egg-milk mixture until well incorporated. Fold in egg white, then pour into prepared crust.Bake until set but jiggly at the center, 20 to 22 minutes. Cool to room temperature on a wire rack, then refrigerate until chilled, about 2 hours. Serve.