Preheat your oven to 350°F (175°C). Line a 9x9-inch baking pan with parchment paper.

In a medium mixing bowl, combine all-purpose flour, granulated sugar, and salt. Cut in the cold butter until mixture resembles coarse crumbs. Press into prepared pan and bake for 15–18 minutes.

In a large mixing bowl, toss sliced peaches with granulated sugar, flour, lemon juice, and vanilla until well-coated. Let sit for a few minutes.

For crumb topping, mix flour, granulated sugar, brown sugar, cinnamon, and salt. Stir in melted butter until crumbly.

Pour the peach filling over the crust, then sprinkle crumb topping evenly. Bake for 45–50 minutes until golden brown and bubbly.

Let the bars cool completely in the pan on a wire rack. Slice into squares and dust with powdered sugar before serving.