1-Preheat the oven and prepare pan: Preheat to 350°F (180°C). Line a 9×13 inch pan with parchment, leaving overhang for easy lifting.

2-Make the crust mixture: Whisk flour, granulated sugar, brown sugar, baking powder, and salt; stir in melted butter, egg, and vanilla until a thick, slightly sticky dough forms.

3-Press the base and blind bake: Reserve 1/3 of dough; press remaining 2/3 evenly into pan; blind bake 10-12 minutes until lightly golden.

4-Prepare the peach filling: Gently combine diced peaches, cornstarch, sugar, lemon juice, and cinnamon until evenly coated.

5-Assemble the bars: Spread peach filling over the pre-baked crust, then crumble reserved dough over the top in small, uneven clumps.

6-Bake the bars: Bake 35-40 minutes until top is golden and filling bubbles at edges, then place pan on a wire rack.

7-Cool completely and slice: Cool in pan at least 2 hours; for cleaner cuts, refrigerate 1 hour, then lift out with parchment and cut into squares.