Preheat an oven to 400 degrees.
To skin the peaches, drop them one at a time in boiling water for 30 seconds and then in an ice bath for 10 seconds, and then just peel the skin off, slice in half, remove the pit, and slice.
Pour the melted butter into a 9 by 13 inch baking dish and set aside.
In a large saucepan, heat the sliced peaches over medium low heat for approximately 10 minutes, stirring occasionally until the peaches are soft. Mix in the cinnamon.
In a large bowl, whisk together 1 cup of sugar, flour, the milk, vanilla, baking powder, and salt. Pour it into the baking dish over the butter and whisk together gently.
Pour the peaches gently over the batter. Add the raspberries to the top, and then sprinkle with the remaining 1/4 cup sugar.
Bake for 25 minutes or until the top is golden and the batter is set.
Serve warm with ice cream.