Preheat the Oven: Set your oven to 350°F (175°C). If you’re using a cast iron skillet, make sure it’s about 9–10 inches wide and at least 2 inches deep to give the cake room to rise.
Prepare the Caramel Base: Pour the melted butter into the bottom of the skillet or a 9×13-inch baking pan. Sprinkle the brown sugar evenly over the butter. The combination will melt together during baking to form that delicious caramelized topping.
Add the Peaches: Arrange the drained peach slices neatly over the brown sugar mixture. You can create a circular pattern or simply spread them out evenly — either way, every slice will be full of sweet, juicy flavor.
Prepare the Cake Batter: In a large bowl, prepare the yellow cake mix according to the package instructions, but substitute the reserved peach syrup for the water. This gives the cake a subtle peach flavor and added moisture. Mix until smooth and well blended.
Assemble the Cake: Gently pour the cake batter over the peaches in the skillet or pan, spreading it out evenly. The batter will be thicker than usual because of the syrup substitution — don’t worry, it will bake beautifully.
Bake: Place the skillet or pan in the preheated oven and bake for 35 minutes, or until a toothpick inserted in the center comes out clean. If you’re using a cast iron skillet, you may need to bake for closer to 1 hour due to the pan’s heat retention and thickness of the batter. Keep an eye on the top; it should be golden brown and slightly firm to the touch when done.
Cool and Invert: Once baked, remove the cake from the oven and let it rest for about 10 minutes. Run a knife gently around the edge, then place a serving platter or large plate over the skillet and carefully invert the cake. The warm brown sugar-peach topping will slide perfectly over the cake, creating a stunning presentation.
