Preheat oven to 350°F. Lightly grease a 9-inch pie dish.
In a mixing bowl, whisk together flour, sugar, salt, and baking powder.
Add in milk and vanilla extract. Stir until well combined.
Stir in the melted butter until the batter is smooth.
Pour batter into the prepared pie dish.
Evenly distribute chopped peaches and blueberries over the batter.
Sprinkle coarse sugar on top, if using.
Bake for 55–60 minutes, or until golden brown and a toothpick inserted comes out clean.
Let cool slightly before serving.