Prepare the crust and set on a cooling rack to cool completely.
In a medium-skillet, melt the butter. Add the chopped pecans and toast, stirring regularly to prevent burning (about 5 minutes).
In a microwavable bowl, melt the white chocolate chips. Stir the toasted pecans into white chocolate and allow to cool, stirring occasionally to keep it from hardening.
Gently stir in the whipped topping until combined. Pour the mixture into the prepared pie shell and refrigerate until set, 2-3 hours. Garnish with white chocolate shavings and extra pecans before serving.