Preheat the oven: to 350°F (175°C). Grease and lightly flour your baking dish or line it with parchment paper. Peel, core, and thinly slice the apples. Set aside. In a medium bowl, whisk together the flour, baking powder, salt, and cinnamon. In a large bowl, whisk the eggs and granulated sugar until light and fluffy.

Add the melted butter, milk, and vanilla extract. Mix until combined. Gradually add the dry ingredients to the wet mixture. Stir just until smooth. Pour half the batter into the prepared baking dish. Layer half the sliced apples over the batter. Sprinkle 2 tablespoons of brown sugar over the apples. Repeat with the remaining batter, apples, and brown sugar.

Place the dish in the oven and bake for 40–45 minutes, or until a toothpick inserted in the enter comes out clean and the top is golden brown. Allow the cake to cool on a wire rack. Dust with powdered sugar before serving, if desired.