Preheat the oven to 350 degrees F. In a medium bowl, stir together the gluten free cookie crumbs, melted butter, and salt until the mixture resembles wet sand. Press it firmly and evenly into the bottom and up the sides of a 9-inch pie dish.Bake for 8 to 10 minutes until set. Let it cool completely.
In a medium saucepan, whisk together the sugar, cornstarch, and salt. Gradually whisk in the milk until smooth. In a small bowl, lightly beat the egg yolks and set aside.
Place the saucepan over medium heat and cook, whisking constantly, until the mixture comes to a boil and thickens, about 6 to 8 minutes. Once it boils and is thick, remove from heat.Slowly pour about 1/2 cup of the hot mixture into the egg yolks while whisking constantly to temper them. Then pour the egg yolk mixture back into the saucepan, whisking vigorously.
Return the saucepan to medium heat and cook, whisking constantly, for 2 more minutes until very thick and bubbling. Remove from heat and immediately add the chopped chocolate, butter, and vanilla. Stir until the chocolate is completely melted and the filling is glossy and smooth.
Pour the chocolate filling into the cooled crust and smooth the top with a spatula. Press a piece of plastic wrap directly onto the surface of the filling to prevent a skin from forming. Refrigerate for at least 4 hours, or until firmly set.
When ready to serve, beat the heavy cream, powdered sugar, and vanilla with an electric mixer until stiff peaks form. Spread or pipe the whipped cream over the chilled pie. Top with chocolate shavings and slice to serve.