2.Combine dough ingredients (except for melted butter) in the bowl of a mixer with a dough hook and mix to a smooth dough. Add more flour or water as necessary to form a ball.
3.Remove from bowl and shape into a smooth ball, brush with melted butter and transfer to a clean glass or ceramic bowl. Set aside to rest, covered, for 2 hours.
4.Toss all filling ingredients together in a medium bowl; set aside.
5.For the breadcrumbs, melt butter until golden brown. Add sugar and cinnamon and stir until sugar is dissolved, then add breadcrumbs and stir for 3 minutes on stove until golden brown. Pour onto a tray and cool.
6.To roll dough, lightly flour a linen tea towel and rolling pin, and place on work surface. Roll dough out to a very thin sheet. Once it reaches approximately 40cm in diameter, carefully lift the dough using your fists and throw it in a circular motion to stretch it out to approximately 1 metre in diameter. Lay the dough back on the surface and arrange in a rough rectangle shape.
7.Scatter breadcrumbs over the end of the dough that is nearest you. Place apple filling on the breadcrumbs and, using the tea towel as a guide, roll the filling inside the pastry until completely enclosed, squeezing the roll together as you go to ensure it remains firm.
8.Gently transfer to a baking sheet, and bake 20-25 minutes until golden brown and cooked through. Brush with extra melted butter as soon as it comes out of the oven and cool for approximately 30 minutes before dusting with icing sugar, slicing thickly and serving with creme anglaise or custard.