Preheat your oven to 350°F (175°C).

In a medium bowl, whisk together the all-purpose flour, baking powder, baking soda, and salt. Set aside.

In a large mixing bowl, cream together the softened butter and granulated sugar for about 3-4 minutes until light and fluffy.

Add the eggs one at a time, mixing well after each addition. Stir in the vanilla extract.

Alternate adding the dry ingredients and buttermilk to the butter mixture, starting and ending with the dry ingredients. Mix until just combined.

In a small saucepan over medium heat, melt 2 tablespoons of butter with the brown sugar until smooth and bubbly.

Pour the brown sugar mixture evenly into the bottom of each muffin cup. Arrange the sliced peaches on top.

Spoon the cake batter over the peaches, filling each muffin cup about two-thirds full.

Bake for 20-25 minutes, or until a toothpick inserted into the center comes out clean.

Let the mini cakes cool in the pan for about 5 minutes before inverting onto a wire rack to cool completely.