Preheat the oven to 350 degrees F. Spray a well-seasoned 9-inch cast iron skillet with nonstick cooking spray.
PREPARE THE PEACHES:
In a small bowl, combine the brown sugar, melted butter and cinnamon. Pour into the skillet and arrange the peaches on top. Set aside.
PREPARE THE BATTER:
In a small bowl, combine the flour, baking powder, baking soda and salt. In a large bowl, use an electric mixer to beat the butter and sugar together until pale yellow. Add the egg and almond extract; beat until combined. Beat in the flour mixture and the buttermilk in parts, alternately; beat until just combined.
Pour the batter into the skillet and spread evenly over the peaches. Bake for 35 to 45 minutes, until a cake tester inserted into the center comes out clean. Cool for 10 minutes in the pan before inverting onto a serving plate. Dust with powdered sugar and serve warm.