Place the flour on a plate and add 1 teaspoon of salt and 1/2 teaspoon pepper. Stir to combine.
Dredge each chicken breast in the flour mixture.
Turn the Instant Pot on, then select SAUTE mode and adjust the heat to MORE.
When the Instant Pot is hot, add the 2 tablespoons of olive oil.
Cook the chicken in a single layer for 3-4 minutes per side, or until browned. You may need to work in batches.
Remove the chicken from the pot and cover to keep warm.
Add the butter and mushrooms to the pot and cook for 3-4 minutes or until mushrooms have softened. Add the garlic and Italian seasoning, and cook for 30 seconds more. Season to taste with salt and pepper.
Add the chicken breasts back to the pot along with the chicken broth.
Seal the pot and select Manual Pressure High for 10 minutes.
When the cooking time has finished, carefully vent the pot to release the pressure.
Place the chicken on a serving plate and cover to keep warm.
Select SAUTE mode then adjust the heat to MORE. Add the cream to the pot and bring to a simmer. Cook for 4-5 minutes or until sauce has slightly thickened.
Pour the mushroom sauce over the chicken. Sprinkle with parsley, then serve.