Preheat your oven to 375°F (190°C).

In a large bowl, combine peaches, blackberries, sugar, lemon juice, salt, and cinnamon. Stir gently and let sit for 5 minutes.

In a separate bowl, whisk together flour, sugar, baking powder, and baking soda. Cut in cold butter until mixture resembles coarse crumbs.

Stir in milk gradually until the batter forms a soft, smooth consistency.

Pour the fruit mixture into a greased baking dish and dollop the batter over the top, leaving gaps for steam.

Bake for 40 to 45 minutes until golden brown, watching for bubbling fruit.

Allow to cool slightly for 10 minutes before serving.