Step 1: Prepare Your Pan and Preheat Oven

Preheat your oven to 350°F (175°C). Line a 9×13-inch baking pan with parchment paper or lightly grease it with butter or cooking spray. The parchment paper will make it easier to lift the bars out once cooled.

Step 2: Make the Crumb Mixture

In a large mixing bowl, combine the melted butter and brown sugar. Stir until smooth. Add the vanilla extract and salt, then mix again.

Gradually stir in the flour until the mixture is evenly combined. The texture should be crumbly, similar to damp sand. Reserve about 1 to 1½ cups of this mixture for the topping.

Press the remaining crumb mixture firmly into the bottom of your prepared pan to form an even crust layer.

Step 3: Prepare the Peach Filling

In another bowl, combine the diced peaches, granulated sugar, cornstarch, cinnamon, nutmeg (if using), and lemon juice. Stir until the peaches are well coated. The cornstarch will help thicken the filling as it bakes.

Spoon the peach filling evenly over the crust layer in the pan, making sure to distribute the fruit and juice across the surface.

Step 4: Add the Crumb Topping

Take the reserved crumb mixture and sprinkle it evenly over the top of the peach filling. Don’t worry if it’s a bit clumpy—that adds to the texture.

Step 5: Bake

Place the pan in the preheated oven and bake for 40–45 minutes, or until the topping is golden brown and the filling is bubbly at the edges.

Remove from the oven and let cool completely in the pan before slicing. For clean, neat bars, refrigerate them for about an hour after cooling to help them set.