Preheat your oven to 180°C (350°F) and prepare an 8x8-inch baking pan with parchment paper.

In a large bowl, mix 1.5 cups of flour, 0.5 cups of granulated sugar, 0.5 cups of brown sugar, 1 teaspoon of baking powder, and a pinch of salt.

Melt 0.5 cups of unsalted butter, let it cool, then add it along with 1 egg and 1 teaspoon of vanilla to the dry mixture. Stir until crumbly.

Press two-thirds of the crumbly dough into the bottom of the prepared pan.

In another bowl, toss 3 cups of diced peaches with 0.25 cups of sugar, 2 tablespoons of cornstarch, 1 tablespoon of lemon juice, and 0.5 teaspoon of cinnamon.

Spread the peach filling over the crust in the pan.

Crumble the remaining dough over the peach filling.

Bake for 35 to 40 minutes until golden brown and bubbling.

Let the bars cool completely in the pan before slicing into squares.