Preheat your oven to 350°F (175°C) and grease a 9×13 inch baking dish.

Cream softened unsalted butter and granulated sugar in a mixing bowl on medium speed for 3-4 minutes.

Beat in the eggs one at a time, then stir in the vanilla extract.

In a separate bowl, whisk together flour, baking powder, salt, and cinnamon; alternate adding this dry mix with milk to the wet ingredients.

Fold in the sliced peaches gently.

Pour the batter into the prepared dish and bake for 30-40 minutes, checking for doneness.

Let cool for 10 minutes before transferring to a wire rack to slice and serve.