Start your heat source: Get a low fire going (and allow it to burn down to embers), preheat your grill to a low-medium heat, or preheat your oven to 375 degrees F.
In a small bowl, mix together granola/raisins/chopped nuts, brown sugar, maple syrup (if using), cinnamon, and salt. Set aside.
Remove any stickers from your apples, wash and dry.
Use a sharp knife to slice a small amount off the top of the apple, then use a small spoon to carve out a deep cavity in the apple. (You can also use a small paring knife or melon baller, if you prefer)It doesn’t need to be super wide the whole way down - I recommend tapering it down - a cone shaped opening - ending shortly below the seeds.Be sure to scoop out all of the apple seeds, but don’t cut through the bottom of the apple - that’s why I don’t use an apple corer for this! Repeat with remaining apples.
One at a time, place a cored apple on a square of heavy-duty aluminum foil, cut side up. Stuff with about ¼ of the brown sugar mixture, top with one piece of butter. Carefully draw up the edges of the foil square over the apple, gathering them on top of the open end - this will help keep the apples upright when cooking.
I like to loosely wrap the apples, then, push foil downward as I’m twisting it together, creating a bit of a base / flat bottom to help it stand upright on the grill grates.
Cook them according to your choice of method, listed in the notes section below.
Whichever way you cook them, keep an eye on your apples - the cooking time will vary wildly based on your heat source, the size and variety of apple used, and how soft you like them.
Once they’re cooked as cooked as you like them, remove them from the grill. Allow the baked apples to cool slightly, then serve hot as-is, or topped with a scoop of vanilla ice cream, caramel sauce - or salted caramel sauce! - and/or whipped cream.