1. Start by making the pie crust. In a large bowl, whisk together the flour, salt, and sugar. Add the cold butter cubes, and use a pastry cutter or your fingers to rub the butter into the flour until the mixture looks like coarse crumbs with some pea-sized bits.
2. Slowly add the ice water, one tablespoon at a time, mixing gently with a fork until the dough just comes together. Be careful not to overwork it. Divide the dough in half, shape each into a flat disc, wrap in plastic wrap, and chill for at least 1 hour.
3. While the dough chills, prepare the filling. In a large bowl, toss the sliced apples with granulated sugar, brown sugar, flour, cinnamon, nutmeg, lemon juice, and salt. Set aside to let the flavors meld.
4. Preheat your oven to 425°F (220°C). Remove one dough disc from the fridge and roll it out on a lightly floured surface into a 12-inch circle. Transfer it carefully to a 9-inch pie plate, letting the excess dough hang over the edges.
5. Pour the apple mixture into the crust, arranging the slices neatly but not too tightly. Drizzle half of the salted caramel sauce evenly over the apples.
6. Roll out the second dough disc and place it over the filling. Trim any excess dough, then crimp the edges to seal. Cut a few slits on the top crust for steam to escape. Brush the top with beaten egg for a glossy finish.
7. Place the pie on a baking sheet to catch any drips and bake at 425°F for 15 minutes. Then reduce the temperature to 350°F (175°C) and bake for another 40-45 minutes, or until the crust is golden brown and the filling bubbles.
8. Remove the pie from the oven and immediately drizzle the remaining salted caramel over the top. Let the pie cool on a wire rack for at least 2 hours before serving to let the filling set properly.

One thing Mama Lu taught me was patience—especially when it came to pies. Rushing that cooling step might leave you with a runny mess, and no one wants that. Trust the process; the wait is part of the reward.