Prepare the Yams:
Preheat your oven to 375°F (190°C). Arrange the yam slices in a single layer in a large baking dish.
In a small bowl, mix together the brown sugar, melted butter, cinnamon, nutmeg, ginger, salt, vanilla extract, and orange juice. Pour this mixture evenly over the yams, ensuring they are well-coated.
Bake:
Cover the baking dish with aluminum foil and bake for 30 minutes. Remove the foil and continue baking for another 15-20 minutes, basting occasionally, until the yams are tender and the syrup has thickened.
Make the Marshmallow Meringue:
While the yams are baking, prepare the marshmallow meringue. In a clean, grease-free bowl, whisk the egg whites with cream of tartar on medium speed until soft peaks form.
Gradually add the sugar, one tablespoon at a time, while continuing to whisk. Increase the speed to high and whisk until stiff, glossy peaks form. Fold in the vanilla extract.
Top and Toast:
Once the yams are done, remove them from the oven and switch the oven to broil. Carefully spread the marshmallow meringue over the yams in an even layer. Use a spatula to create peaks and swirls for a decorative effect.
Place the dish under the broiler for 1-2 minutes, watching closely, until the meringue is golden and lightly toasted. This can happen quickly, so don’t walk away!
Serve:
Let the dish cool slightly before serving. Enjoy the warm, gooey, and delightful combination of sweet yams and marshmallow meringue.