1. Whisk together egg, 3 egg yolks, 1/2 teaspoon salt, pumpkin, and next 5 ingredients in a large mixing bowl until smooth; stir in rice and chocolate morsels. Spoon rice mixture into a lightly greased 1 1/2-quart baking dish. Place dish in a 13- x 9-inch baking dish; add hot water to 13- x 9-inch dish to a depth of 1 inch.
2. Bake at 350º for 15 minutes. Stir rice mixture, and bake 40 more minutes.
3. Beat 3 egg whites and remaining 1/4 teaspoon salt at high speed with an electric mixer until soft peaks form. Gradually add marshmallow crème, beating at high speed about 4 minutes or until stiff peaks form. Spread meringue evenly over top of warm pudding, sealing edges.
4. Bake 15 more minutes or until meringue is lightly golden brown. Serve warm, or cool completely.
TIP: To prevent the meringue from weeping, be sure to spread the meringue over the hot filling. Bake pudding immediately. If serving the dessert at room temperature, cool it away from drafts so that the meringue will maintain its height.
MARY ALLEN'S TIPS: When you whip egg whites, use a large, deep bowl. The larger the bowl, the easier it is to incorporate air.
Egg whites will whip faster if the bowl, beaters, and egg whites are at room temperature. The trick to the best volume is to start with clean, grease-free equipment; any trace of fat won't allow egg whites to whip up. Whip just until stiff peaks form.