The Great Old One warlock patron grants the Awakened Mind feature at 1st level (PHB, p. 110):
Starting at 1st level, your alien knowledge gives you the ability to
touch the minds of other creatures. You can communicate telepathically
with any creature you can see within 30 feet of you.
The mixed use of plural and singular "creature" in the text is causing some debate. I have looked for some sort of official ruling, but I cannot find anything.
Is it possible to communicate with more than one creature at once using Awakened Mind's telepathy?
Since it is one-way communication, and a specific language is not a requirement, it seems as though it should be possible to "broadcast" to the minds you wish to reach out to. And a group of creatures would appear to satisfy the "any creature" wording.
Best Answer
There are numerous existing precedents in the PHB which indicate any means multiple.
The confusion here is centered around a single word, emphasized below:
Example precedent: If you can cast the spell Animate Dead you are able to send telepathic thoughts to your minions collectively. The spell Animate Dead (PHB pg. 212-213) is explicit in the usage of any and all being separate and distinct. Relevant text below:
This is an example of how other abilities and features should be read in the same manual. In this case, any indicates that you can select up to and including all of the minions under your control.
To further support this, pretty much every usage of the word any in the PHB denotes a selection among multiple options. There are literally hundreds of examples, dozens of which exist in the spell category, to peruse.
I am of the opinion that the wording here is indicative of the ability to speak to any creature within its range, which means it's not limited to one. If it was, it would have explicitly stated this in the same manner as a spell like Suggestion does (PHB pg. 279):
Note that suggestion specifies a singular creature, not any creature within range.
Now let's compare it to a similar telepathy spell, Sending (PHB pg. 274):
All instances used here are explicitly singular.
The same applies for Telepathy (PHB pg. 281).
What this all suggests is that any is used when you have multiple targets, and the singular is explicitly stated.
So, with all that being said, logical arguments for both interpretations, singular and collective are sound. Ultimately, and lacking official ruling, this will require DM arbitration in your games. Since it's not 2 way communication without the receiver having some telepathic ability or skill, it's hardly overpowered.
I would personally rule it as able to hit multiple targets since the precedent is amply set by other spells and abilities that the usage of the word any is collective, not singular. When a spell is singular, it is normally explicitly detailed in that manner.