A simple Bosnian desert, well served with whipped cream.
Partially core the apples, ensuring that the seeds and stem are fully removed, but taking care not to go all the way through the apple to the bottom.
Bring water, 25 oz. sugar, vanilla, lemon juice, and reserved apple peels to a boil in a large pot. Reduce heat to a simmer, add apples, and simmer until just tender, about 7 minutes per side. Take care not to overcook the apples or they will fall apart too easily.
Remove apples and let cool. Reserve syrup.
Meanwhile, soak walnuts in hot milk until softened.
Melt butter with remaining 1 oz. sugar, stirring to dissolve sugar. Add to walnut mixture and stir to incorporate.
Fill each apple with 1 Tbsp. of the walnut filling. Pour reserved syrup over top and chill until ready to serve.
Serve topped with whipped cream and a few whole walnut pieces.