I’d definitely recommend the Kaya Butter Coffee. The staff also recommends The Riang Cheeseburger ($18) as it is a crowd favourite.
When we were at Fifteen Nine, we were the only patrons. I gave the excuse that it was a weekday afternoon.
Fifteen Nines felt like a place that had both hits and misses; the food is generally decent but forgettable despite being interesting conceptually — there was the use of very interesting combinations of ingredients but the execution was not exactly the most memorable.