Preheat the oven to 180°C (360°F)
Heat the apple juice and honey together in a small saucepan over law heat, until the honey melts. Set aside.
Core the apple and score the skin around the circumference, so that it splits neatly during cooking. Arrange upright in a small baking dish.
Pour the syrup around the apple and bake, uncovered, for 35 minutes, until tender. Serve drizzled with syrup, with mascarpone if desired.