Preheat the oven to 180°C (350°F).
Peel the apples, leaving the stems intact. Core them carefully to remove the seeds, making sure not to break the apples.
In a mixing bowl, combine the finely chopped walnuts, sugar, breadcrumbs, cinnamon, ground cloves, melted butter, and raisins (if using). Mix until well combined.
Fill each apple with the walnut mixture, packing it in tightly. Place the stuffed apples upright in a baking dish.
In a small saucepan, combine the water, sugar, vanilla extract, and lemon juice. Bring to a boil over medium heat, then reduce the heat and let it simmer for a few minutes until slightly thickened.
Pour the syrup over the stuffed apples in the baking dish.
Bake in the preheated oven for about 30-40 minutes, or until the apples are tender and the filling is golden brown.
Remove the apples from the oven and let them cool slightly.
Enjoy your meal!