To easily peel peaches cut an x in the bottom of each one and submerge in boiling water 30-40 seconds. Remove with a slotted spoon to a colander set over a bowl and as soon as they are cool enough to handle peel with a paring knife and slice.
Preheat oven to 350 degrees F. Butter a 9 x 13 baking pan and set on a large cookie sheet (not heavy-duty) with sides to catch any drips.
In a large mixing bowl stir together the peaches, blueberries, ginger both sugars, cornstarch, lemon juice and vanilla. Pour into baking pan. Dot top with diced butter.
In a medium mixing bowl whisk flour, baking powder, salt and sugar together. Pour in milk and mix well, batter will be thick. Scoop heaping tablespoons of batter and drop over top of fruit. There should be 8 biscuits. In a small bowl mix sugar and cinnamon topping together; sprinkle over the entire top including biscuits.
Bake until golden and bubbling 50-60 minutes. Serve warm, at room temperature or chilled with ice cream or freshly whipped cream. It will be juicy when warm and will set up as it cools. Refrigerate leftovers.