Preheat the oven to 350 degrees F (175 degrees C). Spray a 9x13-inch baking pan with cooking spray.
Arrange peaches in the prepared pan. Scatter butter over peaches, then sprinkle brown sugar evenly over top.
Mix flour, white sugar, baking powder, and salt together in a bowl. Stir oil and beaten egg together in another bowl; add to dry ingredients and stir to combine. Spoon mixture over peaches, then sprinkle cinnamon over top.
Bake in the preheated oven until crust is lightly browned, about 45 minutes.