Melt 1 cup brown sugar and 3 tablespoons butter in bottom of pan. Cover with sliced peaches. Mix 1 egg, 1/2 cup sugar, 1 cup flour, 1/2 cup milk, 1 teaspoon baking powder, 1/2 teaspoon salt, and vanilla. Pour over peaches. Bake at 350 degrees for 30 minutes.