For Tamales, soak corn husks in warm water until soft, about 1 hour. Drain and thoroughly dry corn husks.
Combine pineapple and coconut in medium bowl; set aside.
Beat Spread on medium speed with paddle attachment until fluffy; beat in sugar. Slowly beat in masa harina, then Knorr® Chicken flavor Bouillon and baking powder until mixture looks like a coarse crumble. Slowly add milk until dough is dense and moist.
Spread 1/4 cup masa dough onto each husk. Top with about 2 scant tablespoons pineapple mixture. Fold sides of corn husk to center, wrapping the filling. Fold one end of corn husk up against the seam to seal.
Arrange tamales vertically in steamer basket in a pot over boiling water; top with extra husks. Cover with lid and steam until husks pull away from filling, about 45 minutes. Check water level often and add additional water as necessary to avoid burning tamales.
Meanwhile, for Sauce, melt Spread in medium saucepan over medium heat. Add rum and bring to a boil; boil 1 minute. Whisk together pineapple juice and corn starch. Add to saucepan and bring to a boil over medium-high heat. Reduce heat and cook until slightly thickened, about 1 minute. Serve with tamales.