Heat the oven to 375° F. Butter a deep baking dish.
In a large mixing bowl, mix the orange juice, brown sugar, salt, and apple pie spice. Add the apples and stir to completely coat them. Let them rest as you make the topping.
Place the butter, sugar, salt, and apple pie spice in a medium mixing bowl. Using a fork or pastry cutter, blend them well.
Gradually add in the oats, about 1/2 cup at a time, and mix well until all the oats have been added. The mixture should be crumbly.
Pour the apple mixture into the buttered dish. Sprinkle the oat mixture evenly on top.
Place the dish in the oven and bake for 1 hour, or until bubbly and the topping begins to brown.
Serve warm with vanilla ice cream or whipped cream, if desired.
We used to buy this amazing apple pie spice from an orchard near our home in NJ. We still ask our friends to get it for us when we run out. But it's a blend of cinnamon, nutmeg, and cloves. Here is the closest we were able to reproduce ourselves.
Here are other excellent apple varieties for making this Apple Crisp: