To make the Fruit Filling:
Heat the oven to 400°. Butter or coat with cooking spray a 10 -inch -diameter (2 to 2 1/2 quarts) casserole and set it aside.
In a large mixing bowl, combine the peaches, raspberries, sugar, lemon juice, and flour.
Toss well, then transfer the mixture to the baking dish. Bake on the center oven shelf for 20 minutes.
To make the Cobbler Topping:
Sift the flour, 1/4 cup of sugar, baking powder, and salt into a large mixing bowl.
Add the butter and cut or rub it into the dry ingredients with a pastry blender or your fingers until it is broken into small bits.
In a separate bowl, whisk together the milk, sour cream or yogurt, egg, and vanilla extract until blended.
Make a well in the dry ingredients, then pour in the liquid, stirring just until moistened.
To make the Cobbler:
When the filling is done, remove it from the oven.
Use a tablespoon to spoon the topping here and there over the fruit - so it will look like cobblestones when it's baked - covering as much of it as possible.
Mix the remaining 1 tablespoon of sugar with the cinnamon in a small bowl, then sprinkle evenly over the topping.
Bake the cobbler for 20 minutes or until golden brown. Cool for 10 to 15 minutes before serving. Serves 6 to 8.