Place the sugar in a large heavy-based saucepan. Add 250 ml (8 fl oz/1 cup) water, and stir over low heat, without boiling, until the sugar has dissolved.

Increase the heat to medium–high and bring to the boil. Clip a candy thermometer onto the side of the pan, in the liquid. Cook, without stirring, for 20–25 minutes, until the temperature reaches 150°C (300°F), which is called the 'hard crack stage'. If you don't have a candy thermometer, drop a small spoonful of the mixture into a cup of cold
water. If it sets hard instead of being pliable, it is ready.

Meanwhile, insert clean sticks or thick wooden skewers (even chopstick are good!) into the apples. Line a large, heatproof tray with baking paper. Remove the pan from the heat and allow the bubbles to subside. Add about 6 drops of food colouring, and swirl very briefly with a wooden spoon. Spread sprinkles onto separate saucers.

Dip an apple into the toffee. Tilt the pan slightly and turn the apple to coat evenly. Let the excess drip back into the pan, and dip into the sprinkles. Place onto the tray and leave for 20 minutes, to set hard. Repeat with other apples.
Take great care handling toffee and sugar syrup - this is a job that requires adult supervision!