The pastry for katmer pie falls into the same sort of category as phyllo or strudel: thin sheets of dough brushed with butter, wrapped around a sweet or savoury filling.
Cut in square napkins, or using a ring, cut circle shapes of the puff pastry, brush with a little egg wash before baking and line with fresh coarse homemade breadcrumbs to catch any extra liquid (same as you would do making homemade strudel).