Preheat the oven to 350°F (175°C) and grease or line a 9×9-inch baking dish with parchment paper for easy removal.
In a medium bowl, mix the chopped cherries with granulated sugar and allow the mixture to sit for about 10 minutes, releasing the juices.
In a separate bowl, combine flour, oats, brown sugar, baking powder, and salt, and stir until well mixed.
Pour in melted butter and vanilla extract and mix until crumbly dough forms, adding a splash of water if the mixture seems dry.
Reserve one cup of the crumble mixture for topping and press the remaining mixture firmly into the bottom of the prepared baking dish to form the base layer.
Spoon the cherry mixture evenly over the crumb base.
Sprinkle the reserved crumble over the cherry filling, ensuring it's evenly distributed.
Place in the preheated oven and bake for about 30-35 minutes, or until the top is golden brown.
Allow the bars to cool in the baking dish before cutting them into squares and enjoy warm or at room temperature.