Easy Instant Pot Chicken Madeira

boneless skinless chicken breasts ((about 4-5 breast))

Salt and black pepper

olive oil

mushrooms, (halved)

small yellow onion, (finely diced (about ½ cup))

large garlic cloves, (minced)

Madeira Wine ((see notes))

low sodium beef stock or broth

cornstarch dissolved in 2 tablespoons cold water

butter

fresh parsley, (finely chopped)