Preheat oven to 350ºF. Place brown sugar and butter in a 10 1/2 inch cast-iron  or oven proof skillet. Place skillet in oven about 5 minutes or until butter melts.  Remove skillet from oven and whisk brown sugar and butter mixture until well blended. Arrange fruit slices over brown sugar mixture. In a medium bowl, combine flour, granulated sugar, cinnamon, baking soda, and salt. In a small bowl, whisk eggs, sour cream, oil, and vanilla; beat into flour mixture. Pour batter over fruit; Bake 30 to 35 minutes or until a toothpick inserted into center of cake comes out clean. Remove from oven and place on a wire rack to cool 10 minutes. Run knife around edge of cake; invert onto a serving plate. Serve warm. Serves 10-12.