Preheat oven to 350°F Drain pineapple; reserve 1/2 cup syrup.
In 10-inch cast iron skillet, melt 14 cup margarine.
Remove from heat.
Add 1/2 cup brown sugar and stir until blended.
Arrange pineapple slices in skillet.
Place 1 cherry in center of each slice.
In large mixer bowl, beat remaining 14 cup margarine and 1/2 cup brown sugar until light and fluffy.
Beat in egg and molasses.
In small bowl, combine flour, baking soda, ginger, cinnamon and salt.
In small saucepan, bring reserved pineapple syrup to a boil.
Add dry ingredients to creamed mixture alternately with hot syrup.
Spread evenly over pineapple in skillet.
Bake 30 to 40 minutes or until wooden pick inserted in center comes out clean.
Let stand in skillet on wire rack 5 minutes.
Invert onto serving plate.