Strawberry-Oat Streusel Bars

Preheat oven to 350 degrees F. Line an 8-inch-square baking pan with parchment paper, leaving a 2-inch overhang on two sides. Coat with cooking spray.

Combine oats, brown sugar, all-purpose flour, whole-wheat flour, baking soda, cinnamon and salt in a large bowl. Stir in melted butter. Firmly press 2 cups of the oat mixture into the bottom of the prepared pan. (Reserve the rest for the topping.) Bake until fragrant and set, about 20 minutes. Transfer to a wire rack.

Combine strawberries, preserves, granulated sugar and cornstarch in a medium bowl. Spread the mixture evenly over the crust. Sprinkle with the reserved oat mixture.

Bake until the topping is golden and the filling is bubbling, about 35 minutes. Let cool in the pan for 5 minutes. Using the overhanging parchment, carefully lift the bars out of the pan. Transfer to a wire rack to cool completely, about 1 hour. Cut into 12 bars.