I'd say "I baked two pound cakes" to talk about the cakes as themselves like it's two whole things, but I'm not sure at all, I'll just wait for a native speaker to answer

It is interesting to me to see that Japanese speakers are unsure how to count things in English! Counting in Japanese is one of the most difficult things for me. Just remember that we pluralise nouns - 1 cake; 2 cakes, we don't generally use suffixes to modify the number depending on the noun the way Japanese does。