On a small rimmed baking sheet, spread oats in a thin layer.
Bake until lightly browned, about 12 minutes, stirring halfway through baking. Let cool completely. Leave oven on.
Spray an 8-inch square baking pan with baking spray with flour. Line pan with parchment paper, letting excess extend over sides of pan.
In a medium bowl, stir together cooled oats, flour, granulated sugar, pecans, brown sugar, and salt. Stir in melted butter until crumbly. Gently press half of mixture into bottom of prepared pan.
In a small bowl, stir together jam and cornstarch. Using an offset spatula, spread jam mixture onto prepared crust in pan, leaving about a ¼-inch border around edges. Sprinkle remaining oats mixture on top.
Bake until topping is golden brown and filling is bubbling, 45 to 55 minutes. Let cool completely in pan on a wire rack. Refrigerate for at least 1 hour.
Using excess parchment as handles, carefully remove from pan. Peel parchment away from sides, and cut into bars. Store in an airtight container for up to 3 days.
Recipe by Taste of the South at https://tasteofthesouthmagazine.com/blackberry-jam-bars/