01 - Preheat oven to 350°F. Line a 9x13-inch baking pan with parchment paper, allowing overhang on sides for easy removal.
02 - In a large bowl, combine flour, oats, granulated sugar, brown sugar, baking powder, and salt. Whisk until evenly blended.
03 - Pour melted butter and vanilla extract over dry ingredients. Stir with a spatula until mixture becomes crumbly and fully moistened throughout.
04 - Measure out and 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 a solid crust base.
05 - In a separate bowl, combine cherries, granulated sugar, cornstarch, lemon juice, and almond extract. Toss gently until cherries are evenly coated.
06 - Spread cherry mixture evenly over the pressed crust. Sprinkle 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 actively around the edges.
08 - Let bars cool completely in the pan. Using the parchment overhang, lift the entire slab out and transfer to a cutting board. Slice into 12 bars and serve.