Prepare the crust: Add the flour, sugar and salt to your mixing bowl and mix together.
Add the vegan butter and mix it into the dry ingredients with your hands until you have crumbs.
Add the ice water and mix it into a big ball of dough. If needed, add an extra tablespoon or two of iced water (only if it doesn't want to form into a ball of dough).
Cut the ball of dough into equal halves and form the two halves into two balls.
Place the balls of dough into the fridge for an hour. This lets the gluten in the dough relax and helps to prevent shrinking while it bakes.
When the dough has been in the fridge for an hour, then bring out one of the balls so you can roll it out for your crust.
Roll out one of the balls of dough into a circle wider than the size of a 9-inch round pie dish.
Spray your 9-inch round pie dish with non-stick spray and then place the dough over your pie dish and press it down into the edges of the dish.
Preheat the oven to 350°F (180°C).
Prepare the filling: Add peeled and sliced Granny Smith apples to a mixing bowl.
Add the brown sugar, all purpose flour, cinnamon, nutmeg, salt, lemon juice and vanilla extract and toss with the apples so that they're evenly coated.
Add the filling on top of the pie crust and spread it out evenly. Dot the top of the apple filling with the vegan butter.
Roll out the second ball of dough for your top crust and place it on top of the pie filling.
Trim off any excess dough and then pinch the top and the bottom crusts together to seal it. Press a fork around the edges to create a pattern and to seal it in even more.
Brush the top of the pie with melted vegan butter and sprinkle the top with brown sugar.
Cut slits in the top of the pie for the steam to escape and then place the pie dish onto a parchment lined baking tray (the pie can drip while it bakes) and bake it for 50-60 minutes.
Keep a check on it and at the 50 minute mark if it is showing signs of over-browning and you are seeing the filling bubbling up from the slits, then you can take it out of the oven. If it isn't over-browning then leave it in for the full hour.
Allow the pie to cool for 2-3 hours before slicing and serving.