Preheat the oven to 350 degrees F.
In a medium bowl, whisk the graham cracker crumbs with the brown sugar and salt.
Add the melted butter and stir until the crumbs are evenly moistened.
Press the crumbs evenly over the bottom and up the side of a 9 or 10-inch pie pan to form the crust.
Bake the crust for about 10 minutes, until just set. Let cool completely.
In a bowl, whisk together the lime juice, condensed milk, egg yolks and salt until smooth.
Pour the filling into the cooled crust and transfer to the oven.
Immediately lower the oven temperature to 325 degrees F.
Bake the pie for about 25 minutes, or until set around the edge and slightly jiggly in the center.
Let cool to room temperature, then refrigerate until firm, at least 6 hours or overnight.
Cut into wedges and pile a mound of whipped cream on each slice.
Garnish with lime zest and a slice of key lime.
