Scrub and pat dry the potatoes, then pierce them with a fork. Place the potatoes on a baking sheet. Season with salt. Bake for about 1 hour at about 190°C, until the potatoes are cooked through (test with a skewer). Let the potatoes cool.
Cut the potatoes in half (lengthwise). Using a spoon, scoop out most of the potato flesh, making sure the skin doesn’t tear. Place the potato skins, skin side down, on an oiled baking sheet. Bake for another 8-10 minutes until crispy and golden.
Meanwhile, cut the courgette & chicken into tiny cubes and chop the olives & sundried tomatoes (reserve the oil).
Put these in a mixing bowl (together with a spoonful of the reserved sundried-tomato oil) .
Add the potato flesh and combine with a fork, gently mashing the potato. Add the Parmesan, then season to taste.
When the potato skins are crispy, stuff them with the mixture. Grate some hard cheese on the top if you like then bake or grill for about 10 minutes until golden.
Serve warm with a green salad.