In a medium saucepan, combine the pitted cherries, sugar, lemon juice, and cornstarch. Cook over medium heat for about 10 minutes until mixture thickens.

Line a 9x13-inch or 9x9-inch baking pan with parchment paper and spray lightly with cooking spray.

In a large mixing bowl, combine the flour, quick oats, rolled oats, brown sugar, baking powder, and salt. Stir until blended.

Add the room temperature butter and mix until the mixture resembles coarse crumbs.

Press two-thirds of the crumb mixture into the prepared pan, pour the cooled cherry filling over it, and top with the remaining crumb mixture.

Preheat oven to 350°F (175°C), bake for 30-35 minutes until golden brown and bubbly.

Allow cooling completely in the pan on a wire rack before slicing into squares.