Preheat the oven to 350°F (180°C) and prepare a 9x13-inch pan by greasing or lining with parchment paper.

In a food processor, combine flour, granulated sugar, and salt. Add cold cubed butter and pulse until it resembles coarse crumbs. Reserve 1 ½ cups for topping, press remaining into the pan and bake for 15 minutes.

In a mixing bowl, stir reserved crumb mixture and brown sugar until clumps form.

In a large bowl, mix granulated sugar, flour, cinnamon, and salt. Fold in chopped peaches, then mix in heavy cream until combined.

Pour peach filling over the warm crust and spread evenly. Sprinkle streusel topping generously over the filling.

Bake in the oven for about 45 minutes until the topping is golden and filling is bubbling.

Remove from oven, let cool completely on a wire rack, then refrigerate for at least 2 hours before slicing.