Push a wooden stick firmly into the stalk end of each apple.
Place the remaining ingredients, apart from the oil, in a heavy saucepan and heat gently until the sugar has dissolved. Boil steadily, without stirring, for 5–10 minutes. Dip a pastry brush into cold water and brush around the edges of the pan occasionally to prevent sugar crystals forming.
Fill a glass with cold water and drop 1 tsp of the caramel mixture into the water; it should form a ball. If you can roll the ball between your fingertips and it is hard but not brittle, it has reached the “soft crack” stage and is ready to use. Boil for 1 minute more if not, and repeat until ready.
Remove the pan from the heat. Line a baking tray with lightly oiled non-stick parchment. Dip an apple into the caramel to coat, tilting the pan if necessary, and place the apple upright on the lined baking sheet. Working quickly, repeat with the remaining apples.
Leave until the apples are completely cold and the toffee has hardened.
This recipe is brough to you by Ocado, the online supermarket