Caramelised Celery Tarte Tatin With Parmesan Crust

Ingredients

• 2 whole bunches of celery, remove outer leaves and trim roots but do not separate out the sticks
• 50 g (1.8oz) unsalted butter
• 1 tbsp olive oil
• 1 tbsp dark brown sugar
• 1 tbsp balsamic vinegar
• 1 pinch salt &; freshly ground black pepper
• 25 g (0.9oz) freshly grated parmesan to sprinkle
• 100 g (3.5oz) cold butter, cut into 1cm dice
• 200 g (7.1oz) plain flour
• 8 sage leaves, finely chopped
• 25 g (0.9oz) parmesan, finely grated
• 1 pinch salt