How can I thicken fresh whipped cream for topping on a pie?

Happy New Year Everyone!
Just made a chocolate cream pie and want to top it with fresh whipped cream. How can I thicken the cream so it will stay firm? Can I use knox gelatin and how or what else can I do? Thanks,Richie

[annomy]

Thanks for the tips! I went to a waffle-off today at a friend's house (they supply the batter; you bring the topping and assemble for tasting/judging by everyone else). Great idea for a fun party. My contribution was way outside my comfort zone, but why not? Homemade butterscotch - amazingly easy to make - served over belgian waffles with cognac, bananas and whipped cream. In the running, even if not a winner. For my whipped cream, I added about 1 T nonfat dry milk, 1t sugar, and 1/2 t vanilla. Whipped it ferociously with a vintage 1940s hand mixer and transported it in a semi-chilled, semi-insulated pottery bowl. Held up amazingly for the few hours it needed to, and was really tasty! But who knows; maybe next time I'll leave off the whipped cream and try flambeing...

My girlfriend adds a little bit of sour cream -- not sure how much -- but not enough that you can taste it. It seems to do a great job...

In some German shops and regular grocery stores in large cities, there is a product by Dr. Oetker. It's in a small package of three - usually located in the baking section. Sorry I don't remember the name of it. It works beautifully. The Germans use it in all their cakes with whipped cream.

That is Whip It a whipped cream stabilizer. Excellent Product.

A hint from Marion Cunningham on epicurous.com - I haven't tried it, but Ms. Cunningham should know-and it sounds better than gelatin anyway.

833. To stabilize whipped cream, add 2 tablespoons of nonfat dry milk to every cup of whipping cream before you whip