MIX crumbs and butter. Reserve 1/4 cup crumb mixture; press remaining mixture onto bottom and up side of 9-inch pie plate. Refrigerate until ready to fill.
BEAT pumpkin and marshmallow creme in large bowl with mixer or whisk until blended. Gently stir in 2 cups COOL WHIP; pour into crust. Sprinkle with reserved crumb mixture; cover.
FREEZE 4 hours or until firm. Remove from freezer. Top with remaining COOL WHIP and nuts. Place in refrigerator 30 min. before serving to soften slightly.