Preheat oven to 400*
While oven is preheating, core each apple and place into a greased baking dish. If the apples don't sit flat, you can carefully slice a sliver of flesh off the bottom of the apple so it will sit flat in the dish. You can also scoop out some of the apple flesh if you want but I prefer to leave it all intact.
In a food processor, pulse together oats, pecans, brown sugar, chai spice and salt, then add the butter cubes and pulse a few more times until a crumbly texture is achieved.
Spoon crumble mixture into and on top of each apple. If there is any leftover crumble, pile it up on the top of the apples or sprinkle over any remaining space in the baking dish. Cover lightly with foil and bake for 40-50 minutes or until apples are fork tender. Larger apples may need a bit more time to cook through.
Remove the foil halfway through baking to crisp up the crumble topping, if topping starts to burn before the apples are cooked, cover again with foil until apples are fork tender.
Apples will keep for up to 3 days in the refrigerator in an air tight container. Reheat in the oven if desire but I also like to chop up any leftovers to add to my yogurt or oatmeal bowls!