Set your oven to 180°C and line a loaf tin (or similar baking dish) with baking paper.
Peel, core, and slice your apples as thin as you can. A mandolin works best, but watch those fingers.
In one bowl, mix flour, baking powder, sugar, and cinnamon. In another, whisk eggs, milk, and melted butter. Gradually pour the wet mix into the dry, stirring until smooth. The batter should be thin, that’s the magic.
Pour a little batter into the bottom of the dish, then start layering: apples → batter → apples → batter, until it’s all gone. Finish with a drizzle of the remaining batter and a sprinkle of brown sugar.
Bake for about 1 hour, or until golden and set through. Your kitchen will smell like pure happiness.
Let it cool slightly, then slice and serve with vanilla ice cream, cream, or mascarpone. Eat warm. Sigh dramatically.