This authentic key lime pie starts with a homemade graham cracker crust, then a creamy sweet and tart filling, and fluffy toasted meringue. This is a cool and refreshing dessert, and perfect for summer!
Preheat the oven to 350°F (180°C). Grease a 9" pie dish.
In a medium bowl, combine graham cracker crumbs, brown sugar, and melted butter. Stir together until the butter has been mixed into the other ingredients fully.
Pour crust ingredients into prepared pie dish, and push the crust into the bottom and up the sides of the dish. Bake for 10 minutes and let cool on a wire rack.
Key Lime Filling
Combine sugar, cornstarch, and salt in a medium saucepan. Stir to combine and then mix in heavy whipping cream, milk, egg yolks, and lime juice. Over medium heat, whisk to combine.
Bring the mixture to a boil, whisking constantly. Whisk for another couple of minutes until mixture thickens and coats the back of a spoon.
Remove from heat and immediately add cold butter, lime zest, and vanilla. Whisk until combined. Allow filling to cool slightly at room temperature for about 15 minutes, and then pour it into the crust and smooth into an even layer.
Preheat oven to 425°F (220°C). Beat egg whites in a large bowl until frothy. Add cream of tartar and continue beating until stiff peaks form.
Add sugar in, a tablespoon at a time, until meringue is stiff and glossy. Spoon the meringue over the filling and spread it out so it touches the pie dish. This will prevent the meringue from shrinking.
Bake for 5-7 minutes, or until meringue is golden brown. Store in the refrigerator for up to 4 days.
Instead of a meringue topping, use a whipped cream topping instead.
Key limes or regular limes both work in this recipe.
Use freshly squeezed lemons for best taste. Plus, you need the fresh zest for this recipe.
Zest the lemons before squeezing their juices out. It is not easy to zest a lemon afterwards.
2% milk can be substituted for whole milk. I don't suggest a lighter fat milk than that though.
Feel free to use store bought graham cracker crust if you want.
Salted butter can be substituted for unsalted butter in the recipe. Just omit the extra added salt.