PREHEAT oven to 350F. Line an 8-in square baking dish with foil. Place bacon, cornmeal-side up, in prepared dish. Stir sugar with rum in a small bowl until dissolved. Spoon mixture evenly over cornmeal coating.
ROAST, uncovered, in centre of oven until bacon is warmed through and top is golden brown, 45 to 50 min. Let stand 5 minutes before slicing into 24 thin slices.