Preheat oven to 350 degrees Fahrenheit (175 degrees Celsius) and grease a 9-inch springform pan or round cake pan.

In a medium bowl, whisk together the flour, baking powder, and salt.

In a large bowl, cream the softened butter and granulated sugar until light and fluffy.

Add the egg and vanilla extract to the butter mixture and beat until well combined.

Gradually add the dry ingredients to the wet ingredients, alternating with the milk, and mix until just combined.

Transfer the batter into the prepared pan and smooth the surface with a spatula.

Arrange the peach slices on top of the batter in a circular pattern, pressing down slightly.

Sprinkle the turbinado sugar evenly over the peaches.

Bake for 45 minutes or until the top is golden brown and a toothpick inserted into the center comes out clean.

Allow the cake to cool in the pan for 10 minutes before transferring to a wire rack.