• Preheat the oven to 350°F (180°C). Line a 9x9-inch square baking pan with parchment paper and set aside.

Shortbread Crust

• Whisk the flour, granulated sugar, brown sugar, and salt together in a large bowl. Then stir in the melted butter and vanilla extract with a rubber spatula until a crumbly dough forms.
  240 grams all purpose flour, 50 grams granulated sugar, 25 grams light brown sugar, ½ teaspoon salt, 113 grams unsalted butter, 1 teaspoon vanilla extract
• Reserve about half of the shortbread for the top. Store it in the refrigerator until ready to use. Then press the remaining dough into an even layer in the baking pan, using your hands or the bottom of a measuring cup. Bake for 12-18 minutes or until the edges are golden brown.

Peach Filling

• While the crust bakes, melt butter in a medium saucepan, then add chopped peaches, brown sugar, cinnamon, cornstarch, and salt. Cook on medium-low for 10-15 minutes until the sugar dissolves and the peaches are tender, stirring occasionally. Immediately remove from the heat.
  2 tablespoons unsalted butter, 3 peaches, 73 grams light brown sugar, ½ teaspoon ground cinnamon, 2 teaspoons cornstarch, ¼ teaspoon salt
• Carefully spoon the peach mixture on top of the crust. The crust should still be hot when you do this, but don't worry if it has cooled a little bit. Spread the filling into an even layer with an offset spatula.
• Sprinkle the reserved shortbread crumbs on the top and bake the bars for 30-25 minutes until the edges are bubbling and the crumble is golden brown.
• Let the bars cool for 10 minutes in the pan, then remove them from the pan and place on a wire rack for 1-2 hours. After that, chill them in the refrigerator for an additional 30 minutes-1 hour so they don't crumble and fall apart.
• Cut the bars with a sharp knife and enjoy!