Caramelised celery tarte tatin with parmesan crust recipe

INGREDIENTS

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