Step 1: Prepare the Baking Dish: Preheat the oven to 350F (175C). Grease and flour a 9x13 inch baking pan. This prevents the cake from sticking and ensures easy removal after baking. Alternatively, line the pan with parchment paper, leaving an overhang for easy lifting.
Step 2: Prepare the Peaches: In a medium bowl, gently toss the sliced peaches with granulated sugar and cinnamon (if using). This step helps to draw out some of the peaches' natural juices, creating a flavorful syrup that will further moisten the cake. The sugar and cinnamon also enhance the peaches' sweetness and add a touch of warmth.
Step 3: Mix the Cake Batter: In a large mixing bowl, combine the white cake mix, melted butter, eggs, milk, and vanilla extract. Beat with an electric mixer on medium speed for 2-3 minutes, or until the batter is smooth and well combined. Be careful not to overmix, as this can result in a tough cake.
Step 4: Assemble the Cake: Pour the cake batter into the prepared baking pan, spreading it evenly. Arrange the sugared and spiced peach slices over the top of the batter, ensuring they are evenly distributed. Gently press the peach slices into the batter.
Step 5: Bake the Cake: Bake in the preheated oven for 30-35 minutes, or until a wooden skewer inserted into the center comes out clean. The cake should be golden brown on top, and the peaches should be tender and slightly caramelized.
Step 6: Cool and Serve: Remove the cake from the oven and let it cool in the pan for 15-20 minutes before cutting into squares. Dust with powdered sugar (if using) before serving. The cake can be served warm or at room temperature.
Optional Tips and Substitutions:
For a richer flavor, substitute melted butter with melted coconut oil.
Add a streusel topping made from flour, butter, and sugar for extra crunch.
Use canned peaches in syrup if fresh peaches are not available. Drain the peaches well before slicing and tossing with sugar and cinnamon.
A dash of almond extract can enhance the peach flavor. Add 1/4 teaspoon almond extract to the cake batter.