You will need to add variables one for minutes and one for seconds.
--> add dt (delta-time) to seconds
If seconds >= (is more or equal) 60 (because there are 60seconds in a minute)
--> Add 1 to minutes
--> Subtract 60 from seconds
And just pack it all in, in a Timer running boolean or whatever you want to stop/start it.
And if you want it in a text object do:
Set text to Minutes&floor(Seconds)