Preheat oven to 350°. Line a 13×9-inch baking pan with foil, letting excess extend over sides of pan; spray foil with cooking spray.
In a large bowl, whisk together 1 cup brown sugar, cornstarch, cinnamon, nutmeg, and ginger. Stir in peaches and orange zest and juice until well combined.
In another large bowl, whisk together flour, oats, baking powder, salt, and remaining 1 cup brown sugar. Using a pastry blender or 2 forks, cut in cold butter until mixture is crumbly.
In a small bowl, whisk together sour cream, egg, and vanilla until smooth; stir into flour mixture until combined. Using the bottom of a measuring cup, press three-fourths of flour mixture into bottom of prepared pan. Spread peach mixture onto crust. Sprinkle remaining flour mixture onto peaches.
Bake until crust and topping are browned and is center is set, 40 to 45 minutes. Let cool completely in pan on a wire rack.
Using excess foil as handles, remove from pan, and cut into bars. Store in an airtight container for up to 3 days.
Recipe by Paula Deen Magazine at https://pauladeenmagazine.com/peach-pie-bars/