01 - Preheat oven to 350°F. Line a 9x13-inch baking pan with parchment paper, allowing overhang on sides for easy removal.
02 - Combine flour, oats, granulated sugar, brown sugar, baking powder, and salt in a large mixing bowl.
03 - Pour melted butter and vanilla extract over dry ingredients. Stir until mixture becomes crumbly and evenly moistened throughout.
04 - Reserve 1 ½ cups of the crumb mixture for topping. Press remaining mixture firmly and evenly into the bottom of the prepared pan to form the crust base.
05 - Toss cherries with granulated sugar, cornstarch, lemon juice, and almond extract in a separate bowl until cherries are thoroughly coated.
06 - Spread the cherry mixture evenly over the pressed crust. Sprinkle the reserved crumble topping uniformly across the cherry layer.
07 - Bake for 35 to 40 minutes until the topping turns golden brown and the cherry filling bubbles around the edges.
08 - Let bars cool completely in the pan. Use parchment overhang to lift the entire dessert out, then cut into individual bars.