Preheat your oven to 350°F (180°C). Grease a 9x13-inch baking pan or line it with parchment paper.

In a food processor, combine flour, granulated sugar, and salt, then add the cold cubed butter and pulse until crumbly. Reserve 1.5 cups for the topping.

Press the remaining crumb mixture into the bottom of the pan and bake for about 15 minutes until golden brown.

In a bowl, combine the reserved crumb mixture with brown sugar until large clumps form for the topping.

In another bowl, whisk together sugar, flour, cinnamon, and salt, then toss in chopped peaches. Combine heavy cream with optional vanilla and stir into peach mixture.

Pour the peach filling over the baked crust and top with streusel mixture, covering it completely.

Bake the bars for approximately 45 minutes until the filling bubbles and the topping is golden.

Cool completely on a wire rack, refrigerate for at least 2 hours before cutting into squares.