Sweet Potato Pie with Marshmallow Meringue

Preparation

1. For crust:

   Step 1

   Preheat oven to 350°F. Mix graham cracker crumbs and sugar in medium bowl. Add 6 tablespoons melted butter and stir until crumbs feel moist when pressed together with fingertips, adding 1 tablespoon melted butter if crumb mixture is dry. Press crumb mixture onto bottom and up sides of 9-inch-diameter glass pie dish, building up sides 1/4 inch above rim of dish. Bake crust until set and beginning to brown, about 10 minutes. Cool on rack. DO AHEAD Pie crust can be made 2 days ahead. Cover pie crust and let stand at room temperature.

2. For filling:

   Step 2

   Preheat oven to 350°F. Pierce sweet potatoes all over with fork; place potatoes on rimmed baking sheet. Bake until potatoes are very tender when pierced with fork, about 1 hour 15 minutes. Cool slightly. Cut potatoes open and scoop out pulp. Transfer pulp to processor and puree until smooth. Set aside 2 cups sweet potato puree for filling; cool completely (reserve any remaining puree for another use). DO AHEAD Can be made 1 day ahead. Cover and refrigerate.

   Step 3

   Preheat oven to 350°F. Combine 2 cups sweet potato puree, sweetened condensed milk, and all remaining ingredients in large bowl; whisk until well blended and smooth. Pour filling into crust. Bake pie until puffed around edges and set in center, about 50 minutes. Transfer pie to rack and cool. Refrigerate pie at least 4 hours or overnight.

3. For marshmallow meringue:

   Step 4

   Position rack in top third of oven and preheat to 400°F. Using rubber spatula, scrape marshmallow creme into large bowl. Using electric mixer, beat egg whites and salt in another large bowl until foamy. Add sugar, 1 tablespoon at a time, and beat until stiff and glossy peaks form. Add 1/2 cup beaten egg whites to marshmallow creme and stir with rubber spatula or spoon just until incorporated to lighten (marshmallow creme is very sticky and will be difficult to blend at first, but blending will become easier as remaining whites are folded in). Fold in remaining whites in two additions just until incorporated. Spread meringue over top of cold pie, mounding slightly in center and swirling with knife to create peaks.

   Step 5

   Bake pie just until peaks and ridges of marshmallow meringue are lightly browned, about 4 minutes. Let stand at room temperature until meringue is cool. DO AHEAD: Can be made 1 day ahead. Cover with cake dome; chill. Let pie stand at room temperature 30 minutes.