Preheat oven to 350°F (180°C). Grease a 9x13-inch pan or line with parchment paper, leaving overhang for easy lifting after baking.

To make the crust: Process flour, granulated sugar, and salt in a food processor for a few seconds. Add butter and pulse until crumbly. Set aside 1.5 cups for topping. Press remaining crumbs into the pan to form a crust. Bake for about 15 minutes until edges are slightly browned.

To make the streusel topping: Add brown sugar to the reserved crumb mixture and combine with your fingers to form large clumps.

To make the filling: In a large bowl, mix together sugar, flour, cinnamon, and salt. Add chopped peaches and toss to coat. In another bowl, mix heavy cream and vanilla extract, then pour into peach mixture and stir well.

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

Bake 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.