This is not meant to be definitive, or to start a war between the US and Canada. It's just something I've thought about some, and finally looked into.
Both are built pretty much the same way; from the bottom up:
- dark chocolate coating the whole thing
- plain white marshmallow
- a pretty plain cookie
(I'm not talking about Whippets with the layer of fruity goo between the cookie and the marshmallow. Mallomars don't have that.)
I did a compare-and-contrast tasting today:
- They look very similar. Whippets weigh slightly more than Mallomars: 17 grams each versus 13.5 grams. Mallomars are darker and slightly shorter. Whippets have a sort of "pointy nipple" of chocolate at the side of the top; Mallomars are completely smooth and rounded.
- Whippets' marshmallow is fluffier and more lofty than Mallomars'.
- Whippets' marshmallow is considerably sweeter than Mallomars'.
- The cookie part is comparable. (It's the least interesting part to me, so I didn't fully investigate.)
- Both chocolates are nicely tempered, with a good crispness. Mallomars use simpler chocolate with (to me) a richer flavor. The chocolate on Whippets has more nonchocolate ingredients, has less flavor (for me), and feels waxier. In fact, the first thing I noticed while biting in was how waxy the Whippets chocolate felt.
Since I'm a fan of not-so-sweet sweets, and I prefer really dark chocolate, Mallomars win for me.