- 11 (2 1/4×4 3/4″) graham crackers
- 2 tablespoons sugar
- 1 1/2 teaspoons ground cinnamon
- Pinch kosher salt
- 6 tablespoons unsalted butter, melted
- 1 (14-ounce) can sweetened condensed milk
- 4 large egg yolks
- 7 tablespoons fresh key lime juice
- 2 tablespoons fresh lemon juice
- 1 cup chilled heavy cream
- 2 tablespoons powdered sugar
- A 9″ pie pan
- Place rack in the center of oven and preheat to 350°F.
- Pulse graham crackers, sugar, cinnamon, and salt in a food processor until fine crumbs form. With the motor running, drizzle in melted butter and process until well-combined. Transfer mixture to pie pan and press into bottom and up sides with a flat-bottomed measuring cup.
- Bake crust until golden brown and set, 8–10 minutes. Transfer to a wire rack and let cool to room temperature, about 15 minutes.
- Whisk condensed milk and yolks together in a large bowl. Add key lime and lemon juice and whisk until well-combined (mixture will thicken slightly).
- Pour filling into crust and bake until center is just set, about 15 minutes. Transfer pie to a wire rack and let cool completely (filling will set as it cools), about 1 hour. Transfer to refrigerator and chill until cold, at least 1 hour.
- When ready to serve, whip cream with a whisk or electric mixer to very soft peaks. Sprinkle sugar over cream and continue whipping until it holds stiff peaks. Dollop cream in center of pie (leaving at least a 1″ border of visible pie filling) and serve.
- Pie (without topping) can be made, loosely covered, and chilled for up to 2 days.