For the crust:
- 6 tablespoons unsalted butter, melted, plus more for greasing
- 1 cup chocolate graham cracker crumbs (from 9 whole crackers)
- 1/2 cup finely ground almonds
- 1/3 cup sugar
For the filling:
- 1 1/4 cups fresh lime juice, preferably key lime juice (from 25 key limes or 9-10 limes at room temperature)
- 1 teaspoon finely grated lime zest (about 1 1/2 limes) (use a microplane to zest)
- Two 14-ounce cans sweetened condensed milk
- 2 large eggs at room temperature, lightly beaten
For the whipped cream:
- 1/2 cup cold heavy cream
- 1/2 cup cold sour cream
- 2 teaspoons sugar
- Key lime slices, for garnish (optional)
- MAKE THE CRUST: Preheat the oven to 375° and butter a 9-inch deep-dish ceramic pie plate, or a 10-inch standard glass pie plate. In a food processor, pulse the graham cracker crumbs with the ground almonds and sugar until thoroughly blended. Add the melted butter and pulse until the crumbs are moistened. Press the crumbs evenly over the bottom and up the side of the pie plate to form the crust. (I use the bottom of a dry measuring cup to do this.) Bake for about 20-22 minutes, just until the almonds are lightly browned. Let the crust cool to room temperature.
- MEANWHILE, MAKE THE FILLING: In a bowl, whisk together the lime juice, lime zest, condensed milk and eggs until smooth. Pour the filling into the cooled crust and bake for about 20-30 minutes, until set around the edge and slightly jiggly in the center. Let cool to room temperature, then refrigerate until very firm, at least 6 hours or overnight.
- MAKE THE WHIPPED CREAM: In a bowl, using a handheld mixer, beat the heavy cream and sour cream until soft peaks form, 2 minutes. Beat in the sugar until stiff peaks form, 1 minute. Mound the whipped cream on the pie. Garnish with the key lime slices (if using) and serve.