01 - Preheat oven to 350°F. Combine crushed cookies and melted butter in a medium bowl. Press firmly into the bottom and sides of a 9-inch pie dish.
02 - Bake the crust for 8 to 10 minutes. Remove and allow to cool completely on a wire rack.
03 - In a medium saucepan, whisk together milk, cream, sugar, cornstarch, and salt. Cook over medium heat until thickened and beginning to bubble, about 3 to 5 minutes.
04 - In a separate bowl, whisk egg yolks. Gradually add about 1/2 cup of the hot milk mixture to the yolks, whisking constantly to temper.
05 - Pour the tempered yolks back into the saucepan. Continue cooking while whisking until the mixture thickens further and just begins to boil, approximately 2 to 3 minutes.
06 - Remove from heat. Stir in butter, peppermint extract, and food coloring if desired.
07 - Pour the filling into the cooled crust and smooth the surface. Cover with plastic wrap pressed directly onto the filling to prevent skin formation.
08 - Refrigerate for at least 4 hours until fully set.
09 - Using an electric mixer, beat heavy cream, powdered sugar, and vanilla extract until soft peaks form.
10 - Spread or pipe whipped cream over the chilled filling. Garnish with crushed peppermint candies and serve cold.