Turn Instant Pot to saute mode, then add butter and olive oil. Season chicken with salt & pepper, then coat in flour.
Saute chicken for 1-2 minutes per side until lightly browned. Remove chicken, then add in shallots, garlic and mushrooms, sauteeing until liquid releases from mushrooms.
Stir in wine and salt & pepper, bringing to a boil and cooking until reduced by half. Turn off saute mode, then add chicken broth and chicken back to pot.
Place lid on Instant Pot, press the pressure cook button and set to high, then cook for 2 minutes. The Instant Pot will take about 5-10 minutes to come to pressure, then notify you it's done by beeping.
Press the Cancel button then let the Instant Pot do a quick release of the pressure. Open the lid when pressure gauge has dropped and the lid opens easily. Stir in heavy cream.
Serve chicken marsala with side dish of choice, garnishing with parsley if desired. Enjoy!