Dry the Cornish hen with paper towels.
In a medium bowl, mix butter with your lemon zest, salt, pepper, garlic powder, onion powder, paprika and dried thyme.
Rub the outside and under the skin of the hen with the butter mixture. Add some of the butter mixture to the inside of the cavity of the hen as well.
Stuff half of the lemon wedges into the cavity along with the fresh rosemary.
Turn the Instant Pot Saute function on, when the display reads “hot”, add olive oil.
Once the oil is simmering, add the hen to the pot with the breast side down and cook for 3 mins undisturbed. Flip the Instant Pot Cornish Hen over and brown the other side for about 3 mins as well. Once both sides have been browned, remove the hen and set aside on a plate.
Add the onion and garlic to the Instant Pot insert and cook for a few mins, stirring occasionally.
Add in water and use a wooden spoon to scrape the bottom of the pot.
Cancel the Saute function and add the hen back to the pot with the breast side up.
Add in your potatoes. Put the lid on and turn the release valve to the sealing position.
Pressure cook for 12 mins on High Pressure and use a Natural Pressure Release for 10 mins once done cooking to release the remaining pressure.
Open the lid and use tongs to take out the hen and place it on a baking sheet. Brush the hen with the melted butter.
To finish, set the broiler to 400F / 204C, and broil the hen until golden brown and crispy.
To make the gravy, turn the pot on to sauté again. Use a slotted spoon to remove the onion and garlic from the drippings.
Combine flour and butter to make a ball.
Add butter ball to the simmering drippings and stir well until the gravy thickens.