1. Melt butter in the skillet over low heat. Sprinkle brown sugar over top of butter. Drain peach slices and arrange on top of brown sugar.
2. Prepare gingerbread mix according to directions on package. Carefully spoon over peaches.
3. Cover with vac-control valve closed. Place over low heat and bake 30 minutes or until top springs back when lightly touched with fingers. Remove cover and let stand 2 minutes.
4. Cut around side of cake with a knife. Invert a large platter on top of skillet. Turn over and let stand 1 minute. Remove skillet. Scrape, any syrup out of bottom of skillet and place on cake.
5. Serve warm or cold with whipped cream, if desired.