Preheat your oven to 350°F (175°C).
Wash and core the apples, making sure to leave the bottom intact to hold the filling.
In a mixing bowl, combine the crumbled feta cheese, dried cranberries, honey, and cinnamon. If using, add in the chopped nuts.
Stuff each apple with the feta and cranberry mixture, packing it tightly.
Place the stuffed apples in a baking dish. If desired, cut the butter into small pieces and place a piece on top of each apple.
Add ¼ cup of water to the bottom of the baking dish to create steam while baking.
Cover the dish with aluminum foil and bake in the preheated oven for 20 minutes.
After 20 minutes, remove the foil and bake for an additional 10 minutes, or until the apples are tender and slightly caramelized.
Remove the apples from the oven and let them cool slightly before serving.