Preheat your oven to 350°F (175°C) and grease a 12-cup muffin pan with non-stick cooking spray or butter.

In a medium mixing bowl, combine melted unsalted butter and light brown sugar until smooth, then distribute it into each muffin cup.

Slice the ripe peaches and lay them over the butter-sugar mixture in each muffin cup.

Whisk together the all-purpose flour, baking powder, baking soda, and salt in a medium bowl.

In a large mixing bowl, beat together granulated sugar and softened butter until light and fluffy.

Add the eggs one at a time to the creamed mixture, then stir in the vanilla extract.

Gradually add the flour mixture and buttermilk to the wet mixture, alternating between the two until just combined.

Fill each muffin cup with the cake batter about two-thirds full.

Bake for 20-25 minutes until the tops are golden brown and spring back when lightly touched.

Cool in the pan for 10 minutes, then invert onto a platter.