Preheat your oven to 350°F (175°C). Line a 9x9 inch baking pan with parchment paper, leaving an overhang on two sides for easy lifting.

In a large bowl, whisk together the flour, sugar, baking powder, and salt for the crust mixture.

Cut in the cold cubed butter using a pastry blender or your fingertips until the mixture resembles coarse crumbs. Stir in the egg yolk and vanilla extract until just combined. Reserve about 1 cup of this crumb mixture for the topping.

Press the remaining mixture evenly into the bottom of the prepared baking pan to form the crust.

In a separate small bowl, gently mix the canned cherry pie filling with the fresh lemon juice. Spread the cherry filling evenly over the crust layer.

Sprinkle the reserved 1 cup of crumb mixture evenly over the cherry layer.

Bake for 35 to 40 minutes, or until the topping is golden brown and the filling is bubbly. Let the bars cool completely in the pan on a wire rack (at least 2 hours) before cutting into squares. This chilling time is crucial for clean slices.