Peel and quarter the apples, remove the core and cut into slices.
Place the apple slices in a pan.
Pour in the apple juice.
Add the lemon juice, sugar and rosemary and simmer until the apple pieces begin to break up. Set aside some apple slices and allow to cool.
Peel the potatoes.
Finely grate the potatoes.
Squeeze the potato mixture well with your hands to remove excess liquid.
Put the potato mixture in a bowl with the egg. Add the cornflour and season the mixture with salt and nutmeg.
Pour the apples into a mixing bowl and puree with the blender.
Heat 2 tbsp butter in a pan. Add 2 tbsp of the mixture to the hot fat for each pancake and fry for 4-5 minutes until golden brown. Turn over and cook on the other side for 4-5 minutes. Drain the pancakes on kitchen paper, arrange with the apple sauce on plates, garnish with the reserved apple slices and some lemon balm and serve.