This must be baked high in the oven. Adjust oven rack to 1/3 of way down and preheat oven to 375F. You will need shallow 2 qt casserole, butter it and set aside. Blanche peaches in boiling water (15 seconds if ripe)longer if not quite ripe. Peaches are done if you can push your thumb across the surface and skin wrinkles. Place in bowl of ice water, then peel with fingers. Return partially peeled peaches to boiling water if necessary. slice into wedges.
Wash and drain berries and set aside. Place peaches in casserole, cover with berries. sprinkle with 2 Tbsp sugar (reserve the remaining 3/4 cup & 1 Tbsp). In mixing bowl, sift together flour, 3/4 cup sugar, baking powder and salt. Add unbeaten egg. Beat with fork, then switch to pastry blender. (You may use food processor). Mix until well combined (all dry ingredients incorporated and then do not mix any more).
With large spoon, sprinkle topping evenly over berries, should be a thin, uneven layer (not too thick in any one place). Drizzle melted butter over toping. Mix the cinnamon with the remaining 1 Tbsp sugar and sprinkle over the top. Bake uncovered for 15 minutes. Then increase the temperature to 400F and bake 12-15 minutes more until topping is lightly browned. May be prepared ahead of time, refrigerate it and let it stand at room temperature for about half an hour and bake while eating dinner.