- Preheat oven to 350°F. Line 8-inch square baking pan with foil, extending foil over rim of pan by 2 inches; spray foil with nonstick spray,
- Stir together crumbs, 2 tablespoons of brown sugar, and 1/4 teaspoon of salt in medium bowl. Drizzle with butter and stir to combine. Press into prepared pan. Bake 5 minutes. Maintain oven temperature.
- Meanwhile, to make filling, whisk together sweet potato, milk, 1/3 cup brown sugar, egg, pumpkin pie spice, and remaining 1/4 teaspoon salt in large bowl. Pour filling over hot crust; sprinkle with pecans, Return to oven and bake until filling is set, 50–55 minutes.
- Cool completely in pan on wire rack. Cover and refrigerate until chilled, at least 2 hours or up to 1 day. Lift from pan using foil as handles. Remove foil and cut bars lengthwise into 4 strips; cut each strip across into 4 pieces.
- Per serving: 1 bar cookie
Instead of mashed sweet potato, you can use canned pumpkin in this recipe.