In a large bowl, toss the apples with the lemon juice.

In a large skillet, melt the butter over medium heat. Add the apples, sugar, cinnamon and salt. Cook, stirring occasionally until the apples are tender, about 10-12 minutes. Set aside to cool.

In a medium bowl, whisk together the flour, brown sugar, sugar, cinnamon and salt until well blended. Work the cold butter into the flour mixture with a pastry blender or with your fingertips until it looks sandy. Press together to form chunks. Set aside in the refrigerator until ready to use.

Preheat the oven to 350ºF. (180ºC). Line an 8-inch square baking pan** with parchment paper.

In a medium bowl, whisk together the flour, powdered sugar, baking powder and salt until well blended.

In a large bowl, beat the butter, with an electric mixer at medium speed, until smooth. Add the flour mixture and beat just until the dough comes together.

Press the dough into the prepared baking pan. (To press the dough evenly into the pan, it's helpful to place a piece of parchment paper over the dough when you are pressing it into the pan. Remove the parchment before baking.) Bake until the surface looks evenly light golden brown, about 20-22 minutes. Remove from the oven. Top with the cooked apples. Drizzle with caramel sauce. Top with the crumb topping. Return the pan to the oven and continue baking until the topping looks golden brown and the filling starts to bubble, about 25-28 minutes.

Let cool completely in the pan. Dust the cooled bars with powdered sugar.