Place apples, sugar, 1/4 teaspoon cinnamon, and oil in a medium pot. Cover pot and cook over low heat for about 20 minutes, or until soft.

Meanwhile, line up ladyfingers as tightly as possible in a 9×13-inch (20×30-cm) baking pan. In a medium bowl, whisk together eggs, milk, sugar, one teaspoon cinnamon, and vanilla until thoroughly combined.

When the apples have finished cooking, spread them evenly over the ladyfingers, while trying to fill empty spaces with apple slices. Pour egg mixture over ladyfingers and apples. Cover with foil and refrigerate overnight.

Preheat oven to 350 degrees Fahrenheit (180 degrees Celsius). Bake covered for 20 minutes and uncovered for an additional 25 minutes, until all of the egg mixture is absorbed and ladyfingers are puffy and golden. If desired, dust with confectioners’ sugar or enjoy with maple syrup.