Preheat oven to 350 degrees. Prepare cast iron skillet by rubbing with butter and sprinkling with flour.
In medium bowl combine flour, baking soda, salt, ginger, and cinnamon.
In separate bowl combine butter, brown sugar, molasses and hot water. Mix until butter is almost melted.
Mix in egg and vanilla.
Combine wet and dry ingredients until batter is free of lumps.
Pour batter into skillet. Bake for 30-35 minutes or until knife comes out clean. Let cool and cut into 12 equal slices. Serve with fresh whipped cream and berries.