In a small pot add the butter and heat on medium until melted, add the flour and salt, whisk to combine, add the milk and continue whisking until very thick. Remove from heat, let cool while preparing the rest of the pie.
Roll out the pie crust and fit to the pie/cake pan, with the leftover dough use cookie cutters to cut out desired shapes, strips or use an extra pie crust to cover the top completely.
Cover the bottom and sides of the bottom pie crust with Prosciutto di Parma, top with half the shredded cheese and half the white sauce (using a small spoon drop thick sauce on the cheese), repeat for another layer.
Cover with cut outs, strips or extra pie crust. Brush top with a little milk. Bake for approximately 30 minutes, let sit for 5 minutes, cut and serve. Enjoy!
TO MAKE THE GALETTE
Un-roll the round pie crust (or roll into a circle if using homemade) spread an inside circle (leave approximately one inch edge to cover the filling) with half the white sauce, top with the sliced prosciutto and top with the shredded cheese, then drop spoonfuls of white sauce. Fold the edges over the filling. Bake for approximately 30-45 minutes or until golden. Let sit for 5 minutes before serving. Enjoy!