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

In a medium bowl, combine all-purpose flour, granulated sugar, and salt. Cut in cold butter until the mixture resembles coarse crumbs.

Press the mixture into the bottom of the prepared pan and bake for 15-18 minutes until lightly golden.

While the crust is baking, slice the peaches and toss them with sugar, flour, lemon juice, and vanilla. Let sit for 10 minutes.

In another bowl, mix flour, sugars, cinnamon, and salt. Melt the butter and stir it into the dry mixture until crumbly.

Spread the peach filling evenly over the baked crust, then sprinkle the crumb topping generously.

Bake for 45-50 minutes, watching for a golden topping and bubbly filling.

Let cool completely on a wire rack before slicing into squares.

Dust with powdered sugar if desired, and serve warm or chilled.