For the Crust:

1. Whisk together the flour, sugar, and salt in a large bowl.
2. Using the pastry cutter (you can also use two forks) mix in the cold butter cubes until the butter is pea-sized.
3. Mix the water, vinegar, and ice in a large measuring cup or small bowl.
4. Sprinkle 2 tablespoons of the ice water mixture over the flour mixture, and mix with a pastry cutter or bench scraper until water is incorporated.
5. Add more of the ice water mixture, 1 to 2 tablespoons at a time, using the pastry cutter or bench scraper to mix until the dough just comes together in a ball. It’s OK if some dry bits remain. You don’t want to overwork the dough.
6. Move the dough to a lightly floured surface and shape it into a thick disk. Wrap the dough disk in plastic wrap and refrigerate for at least an hour and up to 3 days. You can also store it in the freezer for up to three months.

For the Filling:

1. While the dough is chilling, prepare the filling by gently mixing the apple slices, brown sugar, flour, lemon juice, and cinnamon in a large bowl.
2. Set aside until ready to use. You can cover and store in the refrigerator for up to 3 days.

For the Salted Caramel Sauce:

1. Next, melt the sugar in a medium saucepan over medium-low heat, constantly stirring, until the sugar is completely dissolved. It will look like golden-brown syrup. Be careful not to burn the sugar.
2. Once the sugar is melted, add the butter slices. It’s normal for the butter to rapidly bubble when added. Just keep stirring until the butter is melted (about a minute), being careful not to splash yourself. 
3. Next, slowly add the cream. Again, the mixture will bubble up when the cold cream is added. If you notice any clumping (this happens to me), remove the mixture from the heat and whisk until combined.
4. Once the sauce is combined, remove from heat and mix in the salt. Allow it to cool slightly before using.
5. You can also store it in an airtight container in the refrigerator for up to 1 month. As the mixture cools, it will thicken. Just reheat on the stove or in the microwave when you’re ready to use it.

To Assemble: 

1. Preheat the oven to 375 degrees. Line a baking sheet with parchment paper.
2. On a lightly floured surface, roll out your dough into a 12-inch circle or shape of your choice.
3. Transfer your dough to the prepared baking sheet. Do this before you add your filling!
4. Arrange the apples (but not the juices) in the center of the dough, leaving a 2-3 inch border. 
5. Drizzle the apples (not the crust) with 3-4 tablespoons of the salted caramel sauce.
6. Fold the edges of the dough in onto the apples, overlapping if necessary. 
7. Brush the crust with the prepared egg wash and sprinkle with the Demerara sugar, if using.
8. Sprinkle with sliced almonds, if using.
9. Bake until the crust is golden brown, about 35 minutes. Make sure to rotate the pan halfway through to ensure even baking.
10. Let cool for at least 10 minutes and drizzle with more salted caramel sauce before serving. Top with ice cream or whipped cream, if desired.