In a food processor, combine flour, salt, and room-temperature unsalted butter.
Gradually add water until you achieve a slightly crumbly texture.
Wrap the dough in cling film and set aside.
Peel and cut apples into medium-sized cubes, placing them in a mixing bowl.
Add flour, cinnamon powder (or baking spices), and lemon juice to the apples. Mix well and let it rest for 15 minutes.
Sprinkle flour on a clean surface.
Divide the kneaded dough into four large and four smaller sections.
Roll out the larger sections to cover the ramekin base, and roll out the smaller sections.
Place the bottom dough into the ramekin, add apple filling, and cover with the smaller dough. Seal edges and poke a few holes on top.
Use a baking brush for an egg wash, then sprinkle caster sugar for a frosted look.
Arrange pies in an Air fryer basket.
Bake at 350°F (177°C) for 15 minutes, then reduce heat to 325°F (163°C) for an additional 7 to 10 minutes.
Remove from the Air fryer and cool at room temperature for 2 hours.
Chill in the refrigerator for 2 hours for the best taste.