Set Instant Pot to SAUTÉ. Melt butter and cook garlic for 1 minute.
Press CANCEL. Add chicken pieces and seasonings.
Break fettuccine in half, layer in criss-cross pattern over chicken.
Pour chicken broth over pasta, ensuring all noodles are submerged.
PRESSURE COOK on HIGH for 8 minutes. Quick release when done.
Open lid, stir pasta and chicken.
Add heavy cream and cream cheese, stir until melted.
Mix in Parmesan and Romano cheeses.
Let stand 5 minutes to thicken.
Garnish and serve hot.