Authentic Key Lime Pie with Whipped Cream

Step 1
Preheat the oven to 350 degrees F (175 degrees C).

Step 2
Put melted butter in a large mixing bowl and add graham cracker crumbs, sugar, and salt; mix until combined. Transfer to a 9-inch pie plate and pat with your fingers on the bottom and up the sides to make the crust.

Step 3
Bake in the preheated oven until very lightly browned, about 10 minutes. Remove from the oven and let cool while you prepare the filling. Leave the oven on.

Step 4
Zest limes until you have 1 1/2 tablespoons for the filling plus some to sprinkle on top of the pie; set aside. Juice all limes; you should have 3/4 cup juice.

Step 5
Combine egg yolks and 1 1/2 tablespoons lime zest in a large mixing bowl with an electric mixer until thick. Add condensed milk and mix until thickened, about 3 minutes. Add lime juice and mix until combined. Pour filling into the cooled crust.

Step 6
Bake in the oven until filling has risen slightly and is mostly set but still slightly jiggly in the center, about 15 minutes.

Step 7
Remove from the oven and let cool for 30 minutes at room temperature. Transfer to the refrigerator and let cool for at least 2 more hours.

Step 8
Mix heavy cream and sugar with an electric mixer until stiff peaks form. Spread on top of the pie and sprinkle with reserved lime zest.