In a small bowl, mix together the flour, salt and sugar. Add in the cold butter (cut in small cubes) and mix until the mixture looks like breadcrumbs.
Add the water and mix until it comes together. Form into a flat disc, wrap in plastic wrap and place in the fridge for at least 20-30 minutes.
Peel, core and thinly slice the apples. Place in a small bowl. Mix together the sugar and cinnamon and add it to the apples. Stir to combine.
Unwrap the chilled dough onto a piece of parchment paper and roll it out to a 6-inch round circle and about 1/8-inch thick. (Tip: Dust the parchment paper with a bit of flour so it doesn’t stick.)
Place the dough and the parchment paper onto a baking sheet.
Place the apple filling in the centre of the dough leaving a 1-inch space around the edges. Dot with 1/2 tablespoon butter (cut into very small pieces). Fold the edges up and over the sides to hold in the apple filling.
Brush the crust with egg wash and sprinkle with ½ tsp turbinado or white sugar.
Bake for 25-30 minutes until the apples are tender and the crust is golden brown.
Notes
Optional: Serve with a scoop of vanilla ice cream.