Preheat oven to 375°F. Pour melted butter into a 9×13-inch baking dish.
Place peaches into pot of boiling water for 30 seconds. Turn off heat and, with a slotted spoon, transfer peaches to a bowl of ice water. Once cool enough to handle, remove skins with a paring knife. Slice peaches and set aside.
Combine granulated sugar, flour, baking powder, and salt, stirring until well blended.
Slowly stir in 1 cup milk until mixture comes together into a batter. Pour batter over butter in baking dish.
In a saucepan, combine peaches, cinnamon, brown sugar, vanilla, and lemon juice. Bring to a boil, stirring frequently. Turn off heat and pour peaches over top of batter.
Bake for 40 minutes or until top crust has become a golden brown color.