Set the oven rack 6 inches underneath the broiler; preheat the broiler. Cut each grapefruit in half. With a grapefruit knife, cut around each section to make them easier to remove once the grapefruit has been broiled. Set the grapefruit on a baking tray. Combine the maple syrup and spices in a small bowl. Spoon and spread over the cut portions of the grapefruit. Place under preheated broiler and cook until the top of the grapefruit is nicely glazed, about 3 to 4 minutes. Serve immediately.
Recipe Options: Use liquid honey instead of maple syrup. Or, mix the spices into a 1/4 cup of brown sugar; sprinkle over the grapefruit and broil until melted and nicely caramelized.