Upside-Down Apple Roll Cake – So Soft, So Magical! Ingredients for the Apple Filling: 5 apples 1/2 cup sugar 1 teaspoon cinnamon For the Cake: 3 eggs 1 cup sugar 1/2 cup milk 1 packet baking powder 1 packet vanilla sugar (or 1 teaspoon vanilla extract) 1.5 cups all-purpose flour Instructions: For the filling: Grate the apples and cook them in a pan with sugar and cinnamon until they release their juices and the liquid evaporates. Once the filling thickens, spread it evenly onto a baking tray lin