Make the Crust
Preheat oven to 350°F (175°C).
Mix graham cracker crumbs, sugar, and melted butter.
Press firmly into a pie dish (bottom + sides).
Bake for 8–10 minutes, then let cool completely.
Prepare the Butterscotch Filling
In a saucepan, whisk brown sugar, cornstarch, and salt.
Gradually add milk, whisking until smooth.
Cook over medium heat, stirring constantly until thickened.
Temper egg yolks: slowly add a bit of hot mixture into yolks, whisking.
Pour yolk mixture back into saucepan and cook 2 more minutes.
Remove from heat, stir in butter and vanilla.
Pour filling into cooled crust.
Cover surface with plastic wrap (to prevent skin) and chill 4+ hours.
Make the Whipped Topping
Beat heavy cream until soft peaks form.
Add powdered sugar and vanilla.
Continue beating until stiff peaks form.
Assemble
Spread whipped cream over chilled pie.
Drizzle with caramel or butterscotch sauce.
Sprinkle nuts or toffee bits if desired.