Heat a medium-sized pot over medium-high heat. Melt butter; add apple slices, sugar and cinnamon; mix through to evenly coat. Cook for 10-15 minutes until apples are soft and tender.Spray a 9x13 dish with nonstick cooking spray. Arrange the diced bread in the baking dish; set aside.In a medium-sized mixing bowl, whisk together the eggs, milk, sugar (or sweetener), vanilla and cinnamon. Pour the egg mixture over the bread. Press bread down into the egg wash to completely soak.Pour the apple pie filling over the top of the soaked bread.In a medium-sized bowl, combine the oats, flour, brown sugar, cinnamon, baking powder and melted butter. Mix well using a spatula or your fingertips,to soak the butter through the dry ingredients. Sprinkle evenly over the soaked bread in the baking dish.Cover with plastic wrap and refrigerate for at least 30 minutes, or overnight.Preheat oven to 175°C | 350°F. Remove baking dish from the refrigerator and bring to room temperature for 20-30 minutes.Then bake for 40-50 minutes until the crisp is golden browned and the casserole is completely cooked through.In small bowl, whisk the glaze ingredients. Drizzle over casserole.Serve warm.