Preheat oven to 350°.
Heat a large nonstick skillet over medium heat. Add first 6 ingredients; cook 5 minutes, stirring occasionally.
Place pear mixture in a 2-quart casserole lightly coated with cooking spray.
Lightly spoon flour into a dry measuring cup; level with a knife. Combine flour, 1/2 cup brown sugar, 1 1/2 teaspoons ginger, and salt; cut in butter with a pastry blender or 2 knives until mixture resembles coarse meal.
Place bread in a food processor; pulse 10 times or until crumbs measure 3/4 cup. Stir breadcrumbs and nuts into flour mixture.
Sprinkle flour mixture evenly over pear mixture. Bake at 350° for 40 minutes or until filling is bubbly and topping is golden.