Preheat the oven to 350 degrees F. Place a 9-inch fluted tart pan with a removable bottom on a rimmed baking sheet.
Combine the graham crackers, almonds, granulated sugar, cinnamon and salt in a food processor. Process until the ingredients are broken down and resembles sand. Transfer to a medium bowl. Pour the melted butter over and stir thoroughly with a rubber spatula.
Transfer the mixture to the tart pan and gently press into an even layer and up the sides of the pan. Then firm pack it so the crust will hold together when sliced after baking.
Bake until golden brown, 12 to 15 minutes. Remove from the oven and let cool on a wire rack.
While the crust cools, make the filling: Combine the 1 1/2 tablespoons lemon zest, the lemon juice, condensed milk and egg yolks in a medium bowl. Whisk until smooth. Pour the filling into the cooled crust.
Bake until the filling is mostly set but still jiggles slightly in the center, 15 to 17 minutes. Remove from the oven and let cool completely in the tart pan on a wire rack at room temperature or in the refrigerator for 1 to 2 hours.
For the topping: Just before serving the pie, whip the cream and confectioners' sugar with an electric mixer in a large bowl, starting on low speed then increasing to medium speed, until soft peaks form.
Pile the whipped cream on top of the pie, leaving a 1-inch border around the edges. Garnish with lemon zest, if desired.