Preheat oven to 350 degrees F. Spray a 9×13-inch pan with non-stick cooking spay or line with parchment paper, leaving enough overhang on the sides for lifting the bars out of the pan after baking. Set aside.

To make the crust: Add flour, granulated sugar, and salt to a food processor. Process a few seconds until combined. Add in the butter and pulse until mixture becomes crumbly and resembles coarse meal. If you don't have a food processor, you can crumble all the ingredients together in a bowl using a pastry cutter.

Set aside 1½ cups of the crumb mixture for the topping. Sprinkle remaining crumbs into prepared pan and press firmly into an even layer to form a crust. Bake for about 15 minutes at 350 degrees, until the edges are slightly browned. While crust is baking, make the streusel topping and filling.

To make the streusel topping: Add brown sugar to the remaining crumb mixture and toss with your fingers to combine until large clumps of dough are formed.

To make the filling: In a large bowl, mix together sugar, flour, cinnamon, and salt. Add peaches and toss to combine.

In a small bowl combine heavy cream and vanilla extract, then stir into peach mixture. Mix well. Pour peach mixture over the crust right from the oven and sprinkle the streusel topping evenly on top.

Bake bars at 350 degrees for about 45 minutes, until juice is bubbling and topping is golden brown. Allow to cool completely on a wire rack.

Refrigerate bars for at least 2 hours to let the filling set before cutting into squares. Bars will keep for 3 days in the refrigerator.