Start by cooking chicken in Instant Pot or Crock pot.
If using IP add chicken, onion, garlic, salt, pepper & BBQ sauce to the pot. Cover & cook on high pressure for 20 minutes
If using crock pot: Add in chicken, onion, garlic, salt, pepper & BBQ to the pot. Cover & cook on high for 6 hours.
Remove from juices & shred.
Cut Hawaiian rolls in half and cover both halves with a little extra BBQ sauce. Place bottom half in a baking dish.
Add shredded chicken on bread. Cover with lots of cheese.
Top with top half of bread and slather with garlic butter.
To make garlic butter:
Melt butter, mix in Parmesan and garlic.
Brush on bread
Bake at 350 for 15-20 minutes. Let cool slightly & serve!