Preheat your oven to 350°F (180°C).

Grease a 9x13-inch baking dish with butter or non-stick spray.

In a medium saucepan, melt the unsalted butter over medium heat, stirring until it turns golden amber and nutty, about 5-8 minutes.

In a large mixing bowl, combine all-purpose flour, brown sugar, granulated sugar, and a pinch of salt. Add the browned butter and stir until crumbly.

Press two-thirds of the crust mixture into the bottom of the prepared baking pan.

In a separate bowl, mix sliced peaches with cornstarch, cinnamon, and vanilla extract. Spread the peach mixture over the crust.

Sprinkle the remaining crust mixture evenly over the peach filling.

Bake for 35-40 minutes until the topping is golden brown and the filling is bubbly.

Allow the crumble bars to cool completely in the pan on a wire rack before slicing.