One at a time, place the pork slices between 2 sheets of waxed paper. Using a meat pounder, pound until a uniform ⅛ inch (3 mm) thick. In a bowl, combine the bread crumbs, cheese, parsley, minced sage, thyme, ¾ teaspoon salt, and ½ teaspoon pepper. Add the egg and egg yolk and mix together to make a sticky mass. Lay a slice of pancetta down the center of each pork slice. Top with about one-eighth of the filling, spreading it beyond the pancetta slightly. Fold in both sides of the pork slice to cover the stuffing partially, then roll up the pork, holding the edges as you work to keep the roll snug. Place a sage leaf lengthwise on the roll, then secure the roll and the leaf with 3 bands of kitchen string. Repeat with the remaining pork slices.
In a Dutch oven or other heavy-bottomed pan just large enough to hold the rolls in a single layer, melt the butter over medium-high heat. Place a colander over a plate or bowl. Put 2 pork rolls in the colander and sprinkle with a few tablespoons of flour. Shake the colander, leaving only a light dusting of flour on the rolls. Transfer to a plate and repeat to flour the other pork rolls. Add the rolls to the pan and cook, turning as needed, until browned on all sides and firm when pressed with your fingertip, about 10 minutes. Transfer the rolls to a plate. Add the wine, scraping up any bits clinging to the bottom of the pan. Stir in ¼ teaspoon salt and ½ teaspoon pepper and return the rolls to the pan. Reduce the heat to low, cover, and cook, turning the rolls twice, until the liquid reduces to a thick sauce, about 15 minutes. Transfer the rolls to a platter. Snip the strings and serve hot. Pass the sauce at the table.