1. Heat oven to 350°F. Lightly coat inside of 4 individual 2-cup baking dishes with vegetable oil spray.
2. Stir together 1 tablespoon corn syrup and 1 tablespoon melted butter in each of 4 baking dishes. Sprinkle each with 1/4 cup toffee. Center pineapple rings on toffee and place cherries in centers.
3. Beat softened butter and sugar in small bowl until blended. Add egg and rum, beating well. Stir together flour and baking powder; add alternately with milk to butter-sugar mixture, beating until smooth. Spoon about 3/4 cup batter into each prepared dish.
4. Bake 25 to 30 minutes or until wooden pick inserted in centers comes out clean. Immediately invert onto serving dishes. Refrigerate leftovers.