Preheat your oven to 425°F (220°C).
If using a store-bought pie crust, place it in a 9-inch pie dish. If making your own, roll it out and fit it into the dish. Consider pre-baking it for 5-10 minutes.
In a large bowl, toss the sliced apples with lemon juice, brown sugar, cinnamon, and a pinch of salt. Allow it to sit for about 10 minutes.
In a saucepan, melt the butter over medium heat. Stir in the caramel sauce and cook for another 2-3 minutes until smooth. Pour this over the apple filling.
Spoon the apple and toffee mixture into the prepared pie crust evenly.
Place the pie in your preheated oven and bake for 15 minutes, then reduce the temperature to 350°F (175°C) and continue baking for 25-30 minutes.
Allow the pie to cool for at least 15 minutes before slicing.