Subbing dairy ingredients in Panna Cotta?

The use of Buttermilk probably gave your instructors panna cotta a slight "tang".

The use of heavy cream gives a richness that you would not get using a low fat milk.

Think of the recipe as a blank canvas and any flavor you want can be added.

I do like the idea of the pumpkin flavor. (although I would be more inclined to make a custard like a creme brule)

One of the nice things about a basic recipe is once you know that well you can "experiment" with flavors.

Have fun playing with your food. (One thing your Mom probably told you never to do)

I always use heavy cream and regular milk. Substituting dairy would mean you are no longer making panna cotta. Because of the gelatin, it will firm up but won't have that crazy, creamy unctuous texture.

One of my favorite versions is holiday appropriate - pumpkin! Basically add about a cup of pumpkin puree to whatever recipe and some pumpkin pie spices. Fantastic.

But the panna cotta I make all the time is just a basic one with some almond extract. I then macerate fresh cherries in Amaretto (I use whatever berries are available outside of cherry season) and a little sugar and use that to top the pannan cotta along with caramelized sliced almonds. It's a triple almond cherry mind-blow!