- With the rack in the bottom position, preheat the oven to 190°C (375°F).
- In a bowl, combine the apples with the sugar and Armagnac. Set aside.
- On a clean surface, stack 6 sheets of phyllo, brushing each with butter before adding the next.
- Line a 27-cm (10 1/2-inch) tart pan with a removable bottom and 2.5-cm (1-inch) rim with the buttered sheets of dough. Trim off the excess dough, leaving enough to overhang the tart pan by 1 cm (1/2 inch) all around. Set aside the trimmings. Pile the apple mixture on the dough and fold the edges of the dough toward the middle. Set aside.
- On a clean surface, brush the remaining sheets of phyllo with butter. Slice each sheet into 3 strips, each about 44 cm (17.5 inches) long. Arrange the dough strips on top of the apples, crumpling them to enhance the impression of height and depth.
- Bake until the top is golden, 35 to 40 minutes.