Preheat oven to 350F/180C. Grease a 9?13-inch pan or line with parchment paper and set aside.

To make the crust: Process flour, granulated sugar, and salt in a food processor until combined. Add butter and pulse until crumbly. Set aside 1? cups of the crumb mixture for the topping. Press remaining crumbs firmly into the prepared pan. Bake for about 15 minutes until edges are slightly browned.

To make the streusel topping: Add brown sugar to the remaining crumb mixture and combine until large clumps form.

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. Pour peach mixture over warm crust and sprinkle streusel topping evenly on top.

Bake bars 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.