Preheat your oven to 350°F (175°C).
Grease a 9x13-inch baking dish.
Drain the sliced peaches, reserving the syrup.
Spread the peaches evenly in the baking dish.
Sprinkle cinnamon and nuts over the peaches if using.
Evenly sprinkle the dry cake mix over the peach layer.
Drizzle the melted butter over the cake mix.
Pour the reserved peach syrup over the top.
Bake for 40-45 minutes until golden brown and bubbly.
Let cool slightly before serving; enjoy warm with ice cream!