1. Position a rack in the center of the oven and preheat to 400 degrees F. Toss pears with the lemon juice and 2 tablespoons of the granulated sugar. Melt butter in a small saucepan over medium-low heat. Set aside to cool, then skim the white foam off the surface and discard. Spoon the melted butter into a bowl, leaving behind the solids at the bottom of the saucepan.

2. Heat 2 tablespoons of the reserved butter in a medium nonstick skillet over medium-high heat. Add pear mixture and cook until pears start to give off juices. Add cranberries, cover, and reduce heat to medium-low. Cook until pears are crisp-tender, about 7 minutes. Remove from heat and stir in 2 tablespoons of the bread crumbs; cool the mixture slightly.

3. Combine remaining 2 tablespoons granulated sugar with allspice and ginger in a small bowl. Cut a piece of parchment paper slightly longer than the phyllo sheets and lay it with a long edge parallel to you. Set the stack of phyllo sheets beside it and cover with a clean kitchen towel. Transfer one sheet of phyllo to the parchment with a long edge facing you. Brush with some reserved butter and sprinkle with 1 teaspoon each of the nuts and sugar mixture. Repeat with each remaining phyllo, replacing the towel as you work. Sprinkle remaining 2 tablespoons bread crumbs over top sheet of phyllo.

4. Spoon the pear mixture across the phyllo about 1 inch from the edge closest to you to make a mound, with a 2-inch border at each end. Using the parchment to help you get started, roll the phyllo tightly over the filling to make a log, seam-side down. Lift the parchment with the strudel onto a baking sheet.

5. Bake until golden, about 30 minutes. Transfer on the baking sheet to a rack to cool. Trim ends with a serrated knife. Dust with confectioners' sugar and serve warm or at room temperature with creme fraiche or whipped cream, if desired.