Preheat your oven to 350°F (175°C). Lightly grease a 9x13 baking dish with non-stick cooking spray or butter.
Open the can of biscuits and cut each individual biscuit into 4 equal quarters.
In a large mixing bowl, combine the apple pie filling, ground cinnamon, and butterscotch chips. Stir to distribute the spices and chips evenly.
Gently fold the biscuit quarters into the apple mixture until every piece of dough is coated with the filling.
Pour the mixture into the prepared baking dish and spread it out into an even layer.
Bake for 25 to 30 minutes, or until the biscuits are puffed and golden brown, and the filling is bubbling hot.
While the casserole bakes, whisk together the powdered sugar and milk in a small bowl until smooth. Add a drop more milk if the glaze is too thick to drizzle.
Remove the bubble up from the oven. Let it cool for 5 minutes, then drizzle the glaze over the warm top. Serve immediately.