Preheat oven to 375ºF and grease a 9-inch pie pan.
Fit pie crust in pie plate, crimping the edges. Set aside.
In a large bowl toss apple slices with lemon juice, coconut sugar, cinnamon, cornstarch (or arrowroot flour) and salt until evenly coated.
In a medium mixing bowl stir together flour, rolled oats, coconut sugar and cinnamon. Add softened butter and use your hands or a fork to mix together until a crumble consistency forms.
Pour apples into the pie crust, mounding them towards the center.
Sprinkle the crumble topping evenly over apples.
Place pie pan on a baking sheet to help prevent any spillage that may happen. Bake for 45-60 minutes or until crust is browned and apples are bubbling. Check the pie a few times while baking to make sure that the crust and topping aren’t browning too much. If that happens cover with tin foil.
Remove from oven and let pie cool to room temperature before cutting so the filling has time to set.
Serve with a scoop of vanilla ice cream or dollop of whipped cream and enjoy!