Preheat oven to 350°F. Place the butter in a 13x9 inch pan and place pan in the preheated oven. Once the butter has melted, remove the pan from the oven.
In a medium sized bowl whisk the flour, 1 cup of granulated sugar, baking powder, and salt. Stir in the milk. Stir until just combined, don’t overmix. Pour this mixture into the 13x9 inch pan, overtop of the butter. Gently smooth into an even layer.
Spoon the peaches mixture over the batter. (Or if using canned peaches**, spoon that over the batter). Sprinkle the top with ground cinnamon, use as much or as little as you'd like. I used about 1/2 to 1 teaspoons worth.
Bake at 350°F for 38-44 minutes or until the top is golden brown and baked through.
Serve warm with a scoop of vanilla ice cream*, if desired.