In a large mixing bowl, whisk the flour, sugar, and salt together. Dissolve the yeast in the lukewarm water and add it to the bowl along with the egg and oil. Mix until a shaggy dough forms.

Knead the dough on a floured surface for 8 to 10 minutes until smooth and elastic. Shape into a ball, cover with a clean kitchen towel, and let rise in a warm spot for 90 minutes, until doubled.

Peel, core, and slice the apples into 5 mm-thick wedges. Melt the 60 g butter in a 30 cm / 12-inch skillet over medium heat.

Add the apples, sugar, and cinnamon to the skillet. Cook for 12 to 15 minutes, stirring occasionally, until the apples soften and the juices reduce to a thick glaze.

Pour in the armagnac and cook for 1 more minute to burn off the raw alcohol edge. Remove from heat and let the filling cool to room temperature.

Heat the oven to 190 C / 375 F. Line a 32 cm / 12.5-inch round baking sheet or pizza pan with parchment.

Divide the risen dough into two pieces, one slightly larger than the other. On a floured kitchen towel, stretch the larger piece with your hands until it's thin enough to see the towel pattern through it, about 45 cm / 18 inches across.

Lift the dough onto the prepared pan, letting the edges hang over the sides. Brush with the melted butter, then spread the cooled apple filling over the center, leaving a 5 cm / 2-inch border.

Stretch the second piece of dough the same way and lay it over the apples. Fold the overhanging edges from the bottom layer up and over the top layer, pleating loosely, then brush the whole top with melted butter.

Bake for 35 to 40 minutes, until the crust is deep golden brown and crackly, rotating the pan once halfway through.

Cool on the pan for 15 minutes, then dust generously with powdered sugar before slicing.