From my Pie cookbook.
1 c. whole milk
2/3 c. sugar
1 c. smooth peanut butter
1 t. vanilla
1 c. cold heavy whipping cream
3 large egg whites, at room temperature
3 tbsp. sugar
1 c. marshmallow creme
Gently warm the milk and sugar in a medium-size saucepan over low heat, stirring until the sugar melts, about 5 minutes. Do not let it boil. Remove from the heat and add the peanut butter, whisking until smooth. Whisk in the vanilla. Pour the mixture into a large bowl, set aside on a wire rack, and let cool to room temperature, whisking occasionally. Refrigerate until it begins to thicken.
Whip the cream until thick. Fold about into peanut butter mixture. Shape the filling into the chilled pie shell (the recipe says to use a chocolate crumb crust, but I used a pastry crust) and smooth the top with a spoon. Cover with a loosely tented aluminum foil and freeze until firm but not rock hard, 3-4 hours.
When you’re almost ready to serve the pie, make the marshmallow meringue. In a large bowl, beat the egg whites with an electric mixer until they hold soft peaks. Gradually add the sugar, 1 tbsp. at a time, beating well after each addition. When the whites are thick and glossy but not dry, add the marshmallow creme and blend on low speed. Fold with a spatula if necessary. Using damp fingers, spread the meringue evenly over the pie, mounding it slightly in the center. Place pie in freezer for about 5 minutes.
Just before serving, preheat the broiler. Set the pie on a baking sheet and place under the broiler. Don’t leave the oven; the meringue will take a very short time to brown. Serve at once. Garnish with peanuts or hot fudge sauce.