Preheat your oven to 350°F (175°C). Grease and flour a 10-inch bundt pan or a 9x13 inch baking dish.

Cream the butter and sugar together in a large mixing bowl until the mixture is light and fluffy.

Add the eggs, one at a time, mixing well after each addition.

Stir in the vanilla extract until well combined.

In a separate bowl, whisk together the flour, baking powder, and salt. Gradually add the dry ingredients to the wet ingredients, mixing just until combined.

Gently fold in the diced peaches (and cinnamon if using) until evenly distributed throughout the batter.

Pour the batter into the prepared pan, smoothing the top with a spatula.

Bake for 50-60 minutes or until a toothpick inserted into the center comes out clean.

Cool in the pan for about 15 minutes before transferring to a wire rack to cool completely.