Set your Pressure Cooker to Saute
Add one tablespoon of butter, onion, Worcestershire sauce, rosemary, and flour into your pressure cooker and saute.
Add beef to your pressure cooker and brown meat.
add carrots, celery, peas, and beef broth
Place the pressure cooker trivet on top of the food.
Place baby potatoes in a piece of tin foil and form a packet.
Place foil packet on top of the trivet
Close pressure cooker lid and seal vent.
Cook on high pressure for 25 minutes
vent and open lid
Remove Trivet with potatoes, and smash the potatoes in a mixing bowl with salt, pepper and the rest of the butter.
Set your Instant pot to saute for 5-8 minutes to thicken the mixture.
Add potatoes on top of Shepherd's pie.