01 - Preheat your oven to 350°F. Line a 9x9-inch baking pan with parchment paper, allowing the paper to extend over the edges for easy removal later.
02 - In a large mixing bowl, whisk together the flour, sugar, baking powder, salt, and cinnamon until thoroughly combined.
03 - Add the cold, diced butter and the egg to the dry mixture. Use a pastry cutter or your fingers to work the butter into the flour until the mixture resembles coarse crumbs with some pea-sized pieces remaining.
04 - Press two-thirds of the crumble mixture firmly and evenly into the bottom of the prepared pan. Use the back of a measuring cup or your fingers to create a compact, even layer.
05 - In a separate bowl, combine the halved cherries, sugar, cornstarch, lemon juice, and vanilla extract. Toss everything together until the cherries are evenly coated with the sugar and cornstarch mixture.
06 - Spread the cherry filling evenly over the pressed crust, ensuring an even layer of fruit across the entire base.
07 - Sprinkle the remaining crumble mixture over the cherry layer, distributing it evenly for a nice textured topping.
08 - Bake for 38 to 42 minutes, or until the top is golden brown and the cherry filling is bubbling around the edges. The crumbs should be set and lightly toasted.
09 - Allow the bars to cool completely in the pan. Once cooled, use the parchment paper overhang to lift the entire slab out of the pan. Cut into 16 equal squares and serve.