Heat the oven to 350 degrees F.
Spray a 1 1/2-quart casserole with cooking spray.
Put the potatoes, cinnamon and ginger in an electric mixer bowl. Beat at medium speed until almost smooth. Add the broth and beat until potatoes are fluffy. Spoon the potato mixture in the prepared dish. Top with the marshmallows.
Bake for 20 minutes or until heated through and marshmallows are golden brown.