To make the filling:
Melt the chocolate in a bowl set over a pan of simmering water. Stir until smooth and remove from heat.
Heat ⅓ of the heavy cream in a small saucepan until steaming, swirling to make sure it heats evenly. Meanwhile, whisk together the egg yolks, sugar, and salt together in a bowl. When the cream is heated, slowly pour it into the egg mixture, whisking continually. When all of the cream has been incorporated, return the mixture to the saucepan and cook over medium heat until thickened, stirring constantly, about 3-5 minutes. Gradually whisk the melted chocolate into the custard until it is all incorporated. Add the mint extract. Let cool to room temperature.
Beat the remaining ⅔ cup heavy cream until stiff peaks form. Fold ⅓ of the whipped cream into the chocolate custard to lighten, then fold in the rest. Pour into the baked pie crust.
To make the topping:
Beat the heavy cream until soft peaks form. Add the sugar gradually while continuing to beat the cream to stiff peaks. Stir in the vanilla extract. Spread on top of the chocolate filling and top with the crust thin mint cookies.
Chill the pie for at least 2 hours in the fridge to set. When ready to serve, bring back to room temperature on the counter for 20 minutes or so before slicing (this is key for simple and clean cut slicing, trust me). Store in the refrigerator.
Note: This recipe made for a very thin pie. I used my shallowest pie dish. If desiring a thicker pie, try doubling the filling recipe.
Calories: 338kcal, Carbohydrates: 24g, Protein: 3g, Fat: 26g, Saturated Fat: 16g, Cholesterol: 114mg, Sodium: 79mg, Potassium: 105mg, Fiber: 1g, Sugar: 18g, Vitamin A: 857IU, Vitamin C: 1mg, Calcium: 44mg, Iron: 1mg