This app was mentioned in 4 comments, with an average of 1.75 upvotes
I've been using Stopwatch and timer + for forever. The UI is a bit dated, but it's a pretty solid app. I don't use any of the advanced features so I can't speak to that, but I use multiple timers when cooking and that works fine.
I've been using Stopwatch and Timer for 4 years now. Cascading timers can be set. Responsive developer. Example: groups of timers we're added only a week after I sent in a feature request. Used it as a professional barista for 2 years for doing simultaneous cupping, poor over, and immersion brewing dial-ins. Timers and stopwatches stay accurate during restarts and crashes. I have run this since Android Gingerbread and I'm now on O, and I have never had an issue at any point. There's also a free version.
Actually is it this one? https://play.google.com/store/apps/details?id=com.jupiterapps.stopwatch