Preheat oven to 325 degrees F (165 degrees C). Grease a baking dish.
Mix peaches with 1/2 cup sugar in a bowl. Arrange in the bottom of the prepared baking dish.
Beat butter and 1 cup sugar together in a bowl until creamy. Add eggs and milk; stir to combine. Mix flour, baking powder, and salt together in a separate bowl; add to butter mixture. Stir until fully incorporated. Pour batter evenly over peaches.
Bake in the preheated oven until center is set and bounces back when lightly pressed, 40 to 45 minutes.