2½ cups (313 grams) all-purpose flour1 cup (200 grams) granulated sugar1 cup (98 grams) quick-cooking oats1½ teaspoons (4.5 grams) kosher salt¾ teaspoon (3.75 grams) baking powder½ teaspoon (1 gram) apple pie spice1 cup (227 grams) unsalted butter, melted1½ teaspoons (6 grams) vanilla extract⅔ cup (79 grams) pecans*, finely choppedBourbon Spiced Peach Filling (recipe follows)
Preheat oven to 350°F (180°C). Spray a 13×9-inch baking pan with baking spray with flour. Line pan with parchment paper, letting excess extend over sides of pan.
In a large bowl, whisk together flour, sugar, oats, salt, baking powder, and pie spice. Gradually stir in melted butter and vanilla until just combined. Press 1¾ cups (425 grams) crumble mixture evenly into bottom of prepared pan. Stir pecans into remaining crumble.
Bake until edges are golden brown and center is dry, lightly golden, and just set, 15 to 20 minutes. Let cool in pan on a wire rack for at least 30 minutes. Leave oven on.
Spoon Bourbon Spiced Peach Filling onto prepared crust. Sprinkle pecan crumble mixture in large clumps on top of filling, leaving a bit of filling exposed.
Bake until topping is light golden brown and set, 30 to 38 minutes, loosely covering with foil during final 4 minutes of baking to prevent excess browning. Let cool in pan for 30 minutes. Refrigerate in pan, uncovered, for at least 2 hours or up to overnight.
Using excess parchment as handles, remove from pan, and cut into bars. Refrigerate in a airtight container for up to 3 days.
*We used Schermer Pecans.