Preheat the oven to 180C/gas 4/fan 160C. Core the apples so you have a hole the size of a pound coin in each one. Make a cut just into the skin around the middle of each apple.
Stand the apples in a shallow baking dish large enough to take all four. Mix together the honey, cinnamon and orange zest, put an equal amount into the cavity of each apple, then pour the orange juice into the dish.
Roast the apples for about 40 minutes, spooning the juices over them occasionally. Then, when the apples are almost ready, spoon the blackberries around and over the top of each apple. Return to the oven for 10 minutes or until the juices start to run. Spoon the blackberries and juices over the apples to serve.