Make the crust
Preheat the oven to 375° and butter a 10-inch 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. Bake for about 20 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 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 and serve.