1-Note: Note: The filling should be poured on a hot or warm crust, so be sure to prepare it while the crust is baking in the oven.
2-Preheat oven to 350F/180C: Preheat oven to 350F/180C. Grease a 9×13-inch pan or line with parchment paper, leaving enough overhang on the sides for lifting the bars out of the pan after baking. Set aside.
3-To make the crust: To make the crust: Process flour, granulated sugar, and salt in a food processor for a few seconds until combined. Add butter and pulse until mixture becomes crumbly and resembles coarse meal. Alternatively, 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, until the edges are slightly browned. While crust is baking, make the streusel topping and filling.
4-To make the streusel topping: 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.
5-To make the filling: 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 warm crust and sprinkle streusel topping evenly on top.
6-Bake bars for about 45 minutes, until: Bake bars for about 45 minutes, until juice is bubbling and topping is golden brown. Allow to cool completely on a wire rack.
7-Refrigerate bars for at least 2 hours: Refrigerate bars for at least 2 hours to let the filling set before cutting into squares.
8-Bars will keep for 3 days in: Bars will keep for 3 days in the refrigerator.