Insert a stick into the centre of each apple and set aside.
Place 1 cup (250ml) corn syrup, the butter and sugar in a medium saucepan over medium heat and stir until well combined.
Bring to the boil and cook for 8–10 minutes (do not stir) or until temperature reaches 140°C on a sugar thermometer.
Remove from the heat and stir in the remaining corn syrup and vanilla.
Dip the apples into the caramel and place on a baking tray lined with non-stick baking paper.
Sprinkle with a few salt crystals. Set aside for 30 minutes or until set.
TIP: Use the same caramel recipe to make caramel popcorn. Stir ready-popped popcorn into the hot caramel then place onto a lined baking tray, in a single layer, to cool completely. Separate the popcorn into individual kernels before serving.