In a blender or food processor, add the eggs, milk, flour, sugar, vanilla, salt, cinnamon and allspice. Blend for 10 seconds. Scrape down the sides. Blend for another 10 seconds. Let the batter rest in the blender for 20 – 25 minutes.
Meanwhile, preheat the oven to 425˚F (220˚C). Place a 10-inch oven-safe skillet on the middle rack of the oven.
Using oven mitts, carefully transfer the skillet to the stove top. Add and melt the butter to coat both the bottom and the sides of the pan. Pour in the batter and make sure to spread evenly on the pan. Carefully place the skillet in the oven. Bake until the pancake is puffed, lightly browned on top the top, and darker brown on the sides and edges, about 15 – 20 minutes. Do not peek and open the oven door while baking.
Meanwhile, in a medium sauce pan over medium heat, melt the butter. Add apple, brown sugar, and cinnamon. Cook until apples are softened, stirring occasionally, about 5 minutes. Add the maple syrup and mix well. Transfer the topping to a serving bowl.
Transfer the pancake to a large serving plate. Dust with powdered sugar. Serve with apple-maple topping.