Preheat oven to 350 degrees F. Grease a deep pie pan or an 8x8-inch baking dish with butter.
In a medium bowl, combine butter, brown sugar, cinnamon, nutmeg, cloves, and rum. Stir to combine well.
Fold in dates and granola.
Core the apples, leave about 1/2-inch at the bottom. Be sure not to core the apples all the way through.
Stuff the apples with about 2 Tbsp of the filling.
Add apples to the baking dish. Gently pour in apple cider into the bottom of the dish, making sure not to pour over the apples.
Bake for 35 minutes, or until soft enough to pierce with a fork.