Hi Foodfan,
Whipped dessert topping is under Pantry Staples --> Other stapes --> Puddings/gelatins/fillings -- but excluding that category will eliminate more than just the specific ingredient, as you correctly said. However, if you put a "-" immediately before the exact ingredient name in parentheses into the search box, it will eliminate all instances of it:
-"whipped dessert topping"
Here is how the search looks in the online recipe library: http://www.eatyourbooks....&online-recipes=true And of course you can filter the search results further however you like.
Hope that helps!