For some low calorie sweet desserts you can try some of the following.
-fat free surgar free ice creams or frozen yogurts
-fat free/sugar free jello puddings
-sugar free gelatin with fat free cool whip
-a small bowl of sweeter cereal like mini wheats
-fat free yogurts come in individual containers and make a great treat
-popcicles are ready grab treats
-the 100 calorie cookie/muffins/cake packs make quick desserts but are not that filling and are high cost.
-ready made crepes with fruit and cool whip or even chilled with fat free/sugar free pudding and shaved chocolate.