Combine yams, orange chunks and pineapple chunks in an 8 inch quiche dish or glass pie plate.
Combine orange juice, peel and cornstarch in measuring cup and stir until cornstarch is dissolved. Cook on high 1 minute. Add butter and stir until melted. Pour over yams.
Sprinkle with brown sugar and spice. Cook on high until heated through and slightly caramelized, basting once, about 8 to 9 minutes. Top with marshmallows and run under broiler until browned.