1. Preheat oven to 350 degrees Fahrenheit.
2. Use half the butter to coat the bottom of four (or six) four-inch ramekins. Sprinkle with the brown sugar. Lay peach slices on top of sugar.
3. In a bowl, combine flour, baking powder, baking soda, salt, sugar, and cinnamon.
4. Combine buttermilk, remaining butter, and vanilla. Add wet ingredients to dry and mix until just combined. Pour batter over peaches. Bake until tops are golden and not wet.
5. Gently release from ramekins, upside down, onto dessert plates.