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In honor of Valentine's Day, let's try making chocolate today.
Literal
Today [topic-は] Valentine [associated-with-にちなんで] chocolate [object-を] make-[try-てみ][volitional-ましょう].
~にちなんで ('in honor of, associated with, commemorating') is a set phrase for doing something because of a connection to an event, person, or anniversary. It's used especially for seasonal or commemorative activities. In Japan, Valentine's Day has a specific tradition: women give chocolates to men, and men reciprocate on 'White Day' (March 14) a month later.