Ingredients

• 1½ cups graham cracker crumbs
• ⅓ cup granulated sugar
• 6 tablespoons unsalted butter, melted
• 4 large egg yolks
• 2 (14-oz) cans sweetened condensed milk
• ¾ cup fresh key lime juice
• 1 tablespoon yellow mustard
• 1 tablespoon lime zest
• ¼ cup salt
• 1 cup heavy whipping cream, for topping
• 2 tablespoons powdered sugar, for topping
• Lime slices, for garnish

Method

1. Preheat your oven to 350°F and set a rack in the center position.
2. In a medium bowl, combine the graham cracker crumbs, granulated sugar, and melted butter, stirring until the mixture resembles wet sand.
3. Press the crumb mixture firmly and evenly into the bottom and up the sides of a 9-inch pie plate, using the flat bottom of a measuring cup for a nice compact crust.
4. Bake the crust for 10 minutes until fragrant and lightly golden, then remove and let cool while you prepare the filling — reduce oven temperature to 325°F.
5. In a large bowl, whisk the egg yolks until they turn pale and slightly thick, about 2 minutes of good steady whisking.
6. Add the sweetened condensed milk, key lime juice, mustard, lime zest, and salt, and whisk until the filling is perfectly smooth and silky — don't rush this step.
7. Pour the filling into the cooled crust, smoothing the top gently with a spatula.
8. Bake at 325°F for 15 minutes, just until the center is set but still has the faintest jiggle when you tap the pan.
9. Let the pie cool completely on a wire rack, then refrigerate for at least 4 hours or overnight — patience here makes all the difference.
10. When ready to serve, whip the heavy cream and powdered sugar together until soft peaks form, and dollop generously over each slice.
11. Garnish with thin lime slices and serve cold — this pie only gets better as it chills.