Wash the apples and remove the core. To keep them upright, make a small cut at the base.
Place the apples in a baking dish with a little water at the bottom.
Sprinkle the apples with ground cinnamon and add the cinnamon stick to the dish.
Add the zest of 1/4 lemon and 1/4 orange, then squeeze their juice over the apples.
Bake for 25 minutes at 180ºC. Baking times may vary depending on your oven, so keep an eye on them. The apples will open slightly when they are done.
Allow them to cool at room temperature, then refrigerate for a few hours before serving.
Notes
Serving ideas: Enjoy them plain, or with whipped cream, coconut cream, melted dark chocolate, or a handful of fresh berries. The contrast between the sweetness of apples and the acidity of berries is especially delicious.