Spread the Dulce de Leche in the bottom of the baked crust. Set aside.

Mix cornstarch and the heavy cream in a heavy bottom saucepan. Blend until cornstarch is dissolved. Whisk in the sweetened condensed milk and egg yolks.

Cook over medium heat until the mixture thickens and become bubbly. Remove from heat, add the butter and vanilla. Pour cream mixture into the prepared pie crust.

Chill pie for at least 2 hours to set.

Just before serving, top with granulated sugar and brown (brûlée) using a kitchen torch or under a broiler. If using the broiler, cover the crust with aluminum foil to prevent burning.

Garnish with sweetened whipped cream if desired. Refrigerate leftovers.