Hi JL. I heartly recommend a trip to Taqueria Mercado on Dixie Highway (Rt 4) in Fairfield. It is an authentice taqueria, general store and mexican bakery and you will find a good tres leches there. The food is super delcious as well so make sure to save room. Post back if you give it a try.
6507 Dixie Hwy
Fairfield, OH 45014
I thought I would check back in with this thread as yesterday I found another source for Tres Leches: Bootsy's. I finally had the opportunity to try Jeff Ruby's newest venture and was pleased to find Tres Leches on the dessert menu. Bootsy's version includes pistashio ice cream and passion fruit sauce.
Bootsy's has caught some heat on this board and on others, but I enjoyed my lunch. It wasn't a mind-blowing experience, but I would certainly return. The Tres Leches is nice, although still not as good as the version I had in Los Angeles.
I too have been looking for Tres Leches in Cincinnati after eating great versions of it in Los Angeles and Las Vegas.
So far I've only found Tres Leches at Abuelo's off of Mason-Montgomery Road in Mason. Abuelo's is a chain, so not a very chowhoundish recommendation. Their version of Tres Leches is worth trying, although it's not as good as the ones I had on the West Coast.
Please let me know if you find any other sources.