1. Preheat the oven to 350℉. Line a 13"x9" baking pan with parchment paper. Make the parchment paper longer on the short edges so it overhangs by at least 2" on either end (you will need this overhang to pull the bars out after they are baked). Spray the bottom with baking spray and then coat lightly with flour. Set aside.

Peach Filling

1. In a large bowl, gently stir together the brown sugar, cornstarch, cinnamon, ginger, and nutmeg. Then, very gently, stir in the peaches, orange zest, and orange juice. Stir until well combined and set aside.

Crust

1. In another large bowl, whisk together the flour, oats, brown sugar, baking powder, and salt. Then, using two knives (or a pastry blender) cut in the butter until the mixture is crumbly, the size of small peas.

2. In a smaller bowl, whisk together the egg, sour cream, and vanilla extract until smooth. Stir the egg/sour cream mixture into the dry ingredients. Mix until combined (but don't over mix). The dough will be crumbly and bit dry, but that's okay.

3. Press 3/4 of the dough into the prepared baking dish. Bake the crust for 10 minutes. Reserve the remaining 1/4 part of the dough for the topping.

4. Remove the crust from the oven and spread the peach filling over the hot crust. Sprinkle the remaining uncooked dough over the top and bake for another 45-50 minutes, until lightly browned and filling is bubbly. Remove the baking dish from the oven and let it cool completely.

   Refrigerate until set overnight (or a minimum of 4 hours).

5. Once the bars are cooled, use the parchment paper to pull the bars out of the pan. Place on a cutting board and cut into bars, small or large, your choice. Serve with a side of whipped cream or ice cream.