• Preheat the oven to 350°F (175°C).

For the caramelized apples and topping:

• In a small bowl, toss the apple slices with 2 tablespoons of the granulated sugar, cinnamon, ginger, nutmeg, and allspice; set this mixture aside.
• Cut the butter into quarters and place the pieces in a deep 10-inch cast-iron skillet or an 8x8 baking dish. Put the pan in the preheated oven for about 3–4 minutes, until the butter has fully melted.
• Remove the hot pan from the oven, sprinkle the brown sugar over the melted butter, arrange the spiced apples evenly on top, and then return the pan to the oven while you prepare the batter.

For the batter and baking:

• In a medium bowl whisk together the flour, the remaining 2 tablespoons granulated sugar, and the salt.
• Whisk in the milk until the mixture is smooth and no lumps remain.
• Add the eggs one at a time, whisking after each addition until fully incorporated. Stir in the vanilla.
• Carefully remove the hot pan from the oven and immediately pour the batter over the apples. Return the pan to the oven and bake for 18–25 minutes, until the center is set and the edges are puffed and lightly browned.
• The German pancake will begin to deflate as it cools; serve warm for the best texture.