In a medium sized mixing bowl, add in the flour, sugar, salt, and cold cubed butter.
Use a pastry cutter or your fingers to cut the butter into the dry ingredients. Continue until you have small chunks of butter distributed throughout the dry ingredients, and no large chunks remain.
Add 2 tbsp. of water into the dough, then use your hands to gently knead the pie crust together. Add in more water ½ tbsp. at a time as needed just until you can form a cohesive ball of dough.
Slightly flatten the pie crust, then wrap it tightly in plastic wrap. Place the dough in the fridge to chill for at least 30 minutes, and for up to 2 days.
Salted Caramel Apples
Wash, peel, and thinly slice the apples, then place them in a medium sized mixing bowl.
Add in the salted caramel sauce, cinnamon, and flour. Mix the ingredients together until each apple slice is covered.
Preheat the oven to 375°F / 190°C. Line a baking sheet with parchment paper or a silicone baking mat, and lightly coat it with flour.
Transfer the chilled pie crust onto the lined baking sheet.
Roll the dough out into a circle that is 11" / 28 cm in diameter. Use a bowl or cup that is ~8" / 20 cm in diameter to gently mark a circle in the center of the pie crust.
Transfer the rolled out crust on to your lined baking sheet.
Arrange the sliced apples into an even layer in the center ring of the pie crust.
Fold the extra dough towards the middle on top of the apples.
Egg wash
Whisk together the egg and milk. Use a pastry brush or your fingers to brush the egg wash on to the top of the crust.
Pat some crushed walnuts on top of the pie crust, if using.
Bake for 30-40 minutes, until the crust turns golden brown.
Once the galette comes out of the oven, top it with some more salted caramel sauce if you want a nice glisten on top of it. Then, top with ice cream and enjoy!