Add pasta to your Instant Pot with broth. Push manual and set the timer to 5 minutes. Do a quick release. Stir in milk, butter, mustard. Add cheese and stir until melted (about 3 minutes). Remove from heat and serve.
Recipe by The Family Fudge at https://thefamilyfudge.com/2018/12/28/easy-instant-pot-mac-n-cheese/