1. Preheat your oven to 375°F (190°C) and line a 9×13-inch baking dish with parchment paper.
2. In a large bowl, combine flour, granulated sugar, brown sugar, baking powder, salt, and cinnamon. Mix well.
3. Cut in the chilled butter using a pastry cutter or your fingertips until the mixture resembles coarse crumbs.
4. Add the beaten egg and mix until the dough starts to come together. Reserve about 1 cup of this mixture for the topping.
5. Press the remaining dough evenly into the bottom of the prepared baking dish to form the crust.
6. In another bowl, toss the sliced peaches with cornstarch, lemon juice, and vanilla extract until well coated.
7. Spread the peach mixture over the crust in an even layer.
8. Sprinkle the reserved crumb mixture over the top of the peaches, covering them as evenly as possible.
9. Bake in the preheated oven for 45-50 minutes, or until the top is golden brown and the peaches are bubbling.
10. Allow to cool completely in the pan before slicing into bars.

As you bake these bars, the kitchen fills with the sweet, comforting scent of peaches and brown sugar—a fragrance that always takes me back to those cherished family gatherings. Remember, the dough might seem crumbly at first, but just like my abuela taught me, trust the process and let your senses guide you.