Preheat the oven to 425°F. Butter a 13 x 9 baking dish.
Apples
Peel the apples and slice them thin.
Melt the butter in a large skillet over medium-high heat. Add the apples, lemon juice, brown sugar, cinnamon and salt and cook, stirring often, for 10 minutes. Add the flour and cook for another 2 minutes.
Remove from heat, and stir in 1 cup of the caramel sauce.
Transfer to the prepared baking dish.
Topping
Combine the flour, baking powder, sugar, and salt in a bowl. Add ¾ cups of the butter pieces, and use a pastry blender to cut into the dry ingredients.
Combine the milk and egg together in a large measuring cup, and pour over the butter and flour mixture. Stir until it comes together - lumps are ok here.
Put together
Sprinkle the remaining 2 tablespoons of butter pieces over the apples.
With clean hands, tear off pieces of the topping and sprinkle over the top of the apples.
If desired, you can sprinkle with more sugar.
Cover with foil and bake for 20 minutes. Uncover, and bake another 20 to 25 minutes, until golden brown.
Serve warm with vanilla ice cream and the remaining caramel sauce.